A few months ago, after my HTC One M8 installed Lollipop version 5.02, I occasionally noticed the stock keyboard would quit working. After researching, the best-first-step solution seemed to be a factory reset. This article outlines the recommended steps.
Starting with a fully-charged phone, or with the phone on power, follow these steps. Several reboots will be needed.
1. Backup all downloads, photos and music to a PC or cloud. Be aware that game scores, and other program settings will be lost.
If all addresses / contacts are stored in Google's Address Book, you have nothing to worry about. Everything will work perfectly.
If the addresses are stored on the phone, export them or they will be lost. See this extensive Keyliner article for recommended steps: Android Phone Address Book Imports. There are some issues with the export and import, outlined in the article. For example, on re-import, whether a number is an Office, Home or Mobile, may be lost.
3. All applications which require a login/password (other than Google's), or programs with internal preferences, will lose their settings. Record the user-id's and passwords you will need. Examples might be your banking apps, VMWare app-authentication, Skype, etc.
4. Email Accounts: Record all of your POP and Imap email account information:
For POP-3/Imap email, record these settings:
SMTP Server Name
Encryption Type: Typically SSL/TLS
Outgoing SMTP Server Name
Encryption Type: Typically SSL/TLS
5. If you use a corporate two-factor authentication program, such as DUO, be sure to get your configuration steps (from your corporate helpdesk) prior to the reset, or you will not be able to login to your corporate network until re-installed and re-authenticated. With my company, they send a specific email/text message to the device.
6. If you are using Google's two-factor authentication, consider printing your emergency access codes (a list of 10 backup codes) or you can have Google send a text message when you first re-login to the phone. Either option will work well, just mentally prepare yourself.
7. I found it was pointless to write down an inventory of my installed applications. When the phone rebooted, it re-installed all of my applications. I was pleasantly surprised. (This is because I was arriving back on the same device. If you are moving to a new phone, some programs may not automatically install.)
8. Power off the phone.
9. Boot the phone into the Hard-Reset recovery screens.
Various manufacturers have different steps for the hardware menus. For the HTC, press and hold the volume-down, then press and hold the power-button. For Samsung, use volume-up and power.
10. From the DOS-like menu, use the volume buttons to select "Recovery", then "Wipe Cache Partition".
This clears a cache that is separate from your application cache. Select reboot and allow the phone to reboot normally. This menu is safe to select any time; it does not damage your installed programs or data. This can fix a variety of odd problems, but this did not help with my keyboard problem. It is wise to clear this cache for other reasons.
11. Shutdown the phone again, return to the Hard-Reset/recovery screen shown above.
12. Select Factory Reset. This will erase all programs and data on the device.
13. Allow the phone to reboot. This may take several minutes. When it reboots, it will apply a large number of updates. e.g. patch 1 of 236, or some-such number (these are operating system patches).
14. When finished, the desktop displays. Open the App Store, select menu "My Apps" and marvel at how many are re-installing. This will take time. Make dinner or something.
Note: During the install, the phone will probably prompt to reboot. Ignore this and let all other applications update.
15. If any expected apps are missing, install from the app store as you would normally. On my phone, all apps arrived correctly.
Once the app store finishes, do the following:
A. In Settings
Confirm you are connected to your wifi network
Confirm Mobile Networks is enabled (by default it will be turned off, which will later show as "data network not available" when you leave the house or office
In Security, set a screen-lock PIN or other security
B. Add program icons to the desktop, by clicking the center-9-dot menu and dragging icons to the Home Screen Pages (desktop)
C. Open each app, setting preferences and logins as needed.
D. If you have other email accounts, use your email reader (or Gmail) to add those accounts to the email program. If you have this well-documented, this is easy. If not, it is a pain.
E. Re-import your exported address book. (If you are using Google to store your addresses, this step is not needed). See this Keyliner article: Android Phone Address Book Imports.
F. If you are using Google Two-Factor Authentication, or Microsoft's Account Manager, launch these applications and re-configure them (details needed).
G For your corporate two-factor (e.g. DUO), follow your corporate instructions.
H. Pair your bluetooth headset or other devices. See this Keyliner article for a Plantronics Headset.
I. Setup Android Device Manager to help you locate or erase lost phones. See this Keyliner article: Android Device Manager can locate a lost phone.
J. If desired, re-copy the backed-up pictures to the phone's DCIM. If you are using Google to backup your photos, they will automatically arrive on the device shortly after the apps are installed; be aware they are not stored locally. A re-copy locally is recommended.
K. Consider disabling some of the phone's unneeded crapware. See this Keyliner article: Disable Cellphone Crapware.
Your comments are welcome.