Do you mean names and passwords in the Password Manager or do you mean that you are no longer logged on to (remembered by) websites after closing and restarting Firefox?

There is a difference between remembering the name and password in the Password Manager and a "remember me" check box on a web page.

The latter usually involves the creation of a special "remember me" cookie that is stored on your computer and that is send to the server.

If that "remember me" cookie is removed or gets corrupted or is not send to the server then the server won't remember you and you need to sign in once again.

• http://kb.mozillazine.org/Websites_report_cookies_are_disabled (Other Solutions)

If Firefox doesn't offer to store passwords in the Password Manager then check that you aren't running Firefox in Private Browsing mode.

• https://support.mozilla.com/kb/Private+Browsing

I mean password manager. And I don't have firefox running in private mode

Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the extensions is causing the problem (switch to the DEFAULT theme: Firefox (Tools) > Add-ons > Appearance/Themes).

• Don't make any changes on the Safe mode start window.
• https://support.mozilla.com/kb/Safe+Mode

• https://support.mozilla.com/kb/Troubleshooting+extensions+and+themes

I did not solve the problem

Does Firefox offer to store passwords (i.e do you get a Key icon on the location bar)?

Do you have any passwords saved?

• Tools > Options > Security: Passwords: "Saved Passwords" > "Show Passwords"

No, firefox does not offer to store passwords and there are no passwords saved.

It is possible that there is a problem with the files key3.db and signons.sqlite that store the encrypted names and passwords in Firefox.
Rename the files key3.db and signons.sqlite in the Firefox profile folder.
You can add .old to the file names (key3.db.old and signons.sqlite.old) or move them to another folder to make it possible to undo the action.
You need to set a new Master Password after renaming or deleting key3.db and all currently saved passwords are lost.
If that has worked then you can remove the renamed files that are no longer needed.

See:

• "Troubleshooting" in http://kb.mozillazine.org/Password_Manager