Have you reviewed your programming to see if the "lost channels" are still there? Hit HOLD and then scroll through the programmed channels using the "large knob". It should be pretty easy to review if you have only 8 channels. This should also let you look to see if the channels were inadvertently Locked/Out.
To add slightly to what RMason has suggested, you might want to
download & install FreeSCAN. Connect the cable that came with the scanner to your PC & download your programming into the software. You can use the software to review what is already programmed, and save that to your PC as a "just in case" backup.
Sorry, I was on shift the other day. I tried it and it scans and ends up at a radio station with music, see pic.
That FM radio station appears to be programmed. Possibly, at some point, you ran either Close Call, or did a search for new frequencies with Auto Store active. When doing a search, or using Close Call, if Auto Store is activated, it will store any new frequency it runs across and adds them to your programming file. In regards to Close Call. or Search, you can use
Broadcast Screen so that the scanner does not 'find' FM radio or broadcast TV channels.