Are you using sync? Are you using a password add-on?

Profile data can be removed or not recorded several ways;

• 1) Running Firefox in Private Mode (nothing is recorded)
• 2) Privacy settings; (In the address bar, type about:preferences#privacy<enter>)
• 3) Many disk cleaners and anti-virus type programs can remove data from browsers. Open their settings and have them leave the browsers alone.
• 4) Mal-ware.

In the event that the passwords information is lost, you should record all information in a separate text file somewhere else on your hard drive, or written down. You can easily copy and paste if you need to do so. If you are concerned about someone else looking at that file, you can compress it using a password.

These can't get your data back, but will help in the future.

These add-ons can be a great help by backing up and restoring Firefox

https://addons.mozilla.org/en-US/firefox/addon/febe/ FEBE (Firefox Environment Backup Extension)

FEBE allows you to quickly and easily backup your Firefox extensions, history, passwords, and more. In fact, it goes beyond just backing up -- It will actually rebuild your saved files individually into installable .xpi files. It will also make backups of files that you choose.

https://addons.mozilla.org/en-US/firefox/addon/opie/ OPIE

Import/Export extension preferences

No, nothing has changed on my computer other than updating Firefox. I don't use Sync or any password add-on and I'm not using Private Mode. My anti-virus is AVG and I've used it for years with no problems.

Today I have a problem with every bookmark. They all lost their icons. Now every icon is a grey round icon that looks like a globe.

I forgot to mention, I do have FEBE. That's how I am able to get my passwords and logins back, but it's a pain to have to backup up every day and restore every day.

Start your computer in Safe Mode. Start Firefox. Restore the data if you need to. After close it.

Reboot in Safe mode. Is the problem still there?

http://encyclopedia2.thefreedictionary.com/Linux+Safe+Mode Starting Any Computer In Safe Mode; Free Online Encyclopedia

I restarted it in safe mode twice and I did not have to restore any data. It was all there. I then restarted it normally and the logins and passwords were gone again. My bookmark icons were still there.

Okay, getting somewhere.

Just In Case, You may have ad/mal-ware. Further information can be found in this article; https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware?cache=no

Run most or all of the listed malware scanners. Each works differently. If one program misses something, another may pick it up.

Start your Computer in safe mode. Then start Firefox.

Restore the data. Close Firefox. Wait 20 seconds.

Open Firefox. Is the data still there?

If nothing goes wrong with the second startup, then something in the computer is removing the data.

https://support.mozilla.org/en-US/kb/how-to-fix-preferences-wont-save

Note: Some software, like Advanced SystemCare with Surfing Protection, can protect files in the Firefox profile folder against changes. If you have such software then check the settings or uninstall this software.

FredMcD said

Okay, getting somewhere. Just In Case, You may have ad/mal-ware. Further information can be found in this article; https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware?cache=no Run most or all of the listed malware scanners. Each works differently. If one program misses something, another may pick it up.

I ran all the programs and they all reported no problems other than some tracking cookies. Somewhere along the line my bookmark icons changed back to the grey round ones again.

I tried disabling my anti-virus and re-booting, but that didn't help. My logins and passwords were gone when I opened Firefox.