Can you attach a screenshot to see if that helps to identify the problem?

• http://en.wikipedia.org/wiki/Screenshot
• https://support.mozilla.org/kb/how-do-i-create-screenshot-my-problem

Use a compressed image type like PNG or JPG to save the screenshot.

Clear the cache and the cookies from sites that cause problems.

"Clear the Cache":

• Tools > Options > Advanced > Network > Cached Web Content: "Clear Now"

"Remove Cookies" from sites causing problems:

• Tools > Options > Privacy > Cookies: "Show Cookies"

You can check the network.http.* prefs on the about:config page.

Reset network.http prefs to the default value via the right-click context menu -> Reset if they are user set (bold).

• http://kb.mozillazine.org/about:config

If you reset Firefox then a new profile is created and some of your data (bookmarks, passwords, cookies, form data) is automatically imported and your current profile will be moved to the desktop (Old Firefox Data).

• https://support.mozilla.org/kb/reset-firefox-easily-fix-most-problems

I attached a picture and tried what you said! It again worked temporarily but I had to reset it again after a while.

Seems that you are missing CSS files.

Does it help if you reload and bypass the cache?

• Press and hold Shift and left-click the Reload button.
• Press "Ctrl + F5" or press "Ctrl + Shift + R" (Windows,Linux)
• Press "Command + Shift + R" (MAC)

Which security software (firewall, anti-virus) do you have?

A possible cause is security software (firewall,anti-virus) that blocks or restricts Firefox or the plugin-container process without informing you, possibly after detecting changes (update) to the Firefox program.

Remove all rules for Firefox and the plugin-container from the permissions list in the firewall and let your firewall ask again for permission to get full unrestricted access to internet for Firefox and the plugin-container process and the updater process.

See:

• https://support.mozilla.org/kb/Server+not+found
• https://support.mozilla.org/kb/Firewalls