Hi dhanvarsh, I understand that you are repeatedly being asked for a master password. First try to reset it:

• Reset your Primary Password if you've forgotten it and then remove it: https://support.mozilla.org/en-US/kb/use-master-password-protect-stored-l...

Since it still prompts for one, see this as it suggests to delete the encryption keys, but this may delete other stored items here, so make a back up first: Back up and restore information in Firefox profiles

Do you have saved any passwords in the Password Manager?

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

It is possible that there is a problem with the key3.db file (encryption key) and the logins.json file (encrypted names and passwords) in Firefox.

You can rename the key3.db file (key3.db.old) and logins.json file (logins.json.old) or move these files to another folder to make it possible to undo the action. Rename or delete a possible signons.sqlite file (signons.sqlite.old) used by older Firefox versions as well.

You can use this button to go to the current Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder)
• http://kb.mozillazine.org/Profile_folder_-_Firefox