There are a few reasons why images may be broken:

• Images are blocked or disabled: see Fix problems that cause images to not show

• Bad item stored in the Browser Cache: Follow the steps at How to clear the Firefox cache.

• An extension like Adblock Plus, an antivirus toolbar, or Real Player Browser Record Plugin may be causing the problem: see Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems

Do you remember the text of that pop-up?

Check the image exceptions: Tools > Options > Content: Load Images: Exceptions
See Settings for web content, pop-ups, fonts, and languages

• A way to see which images are blocked is to click the favicon (Site Identification icon) on the left side of the location bar.
• A click on the "More Information" button will open the Security tab of the "Page Info" window (also accessible via "Tools > Page Info").
• Open the Media tab of the "Page Info" window.
• Select the first image and scroll down though the list with the Down arrow key.
• If an image in the list is grayed and there is a check-mark in the box "Block Images from..." then remove that mark to unblock the images from that domain.

I also Have no sound on my computer anymore!!!!

See What to do if Firefox won't play any sounds and Fix common audio and video issues

You can click the Volume icon on the Windows Taskbar near the clock and click the Mixer link at the bottom to open the mixer.
You can adjust the volume level for each application in that window, so make sure that Firefox is not muted or set at a low level.
You will only see the Firefox program in the Mixer if you are on a website that plays sound.

Were you able to restore the blocked images to reappear?