I recently just took home an Apple IIe computer. Everything worked the day that I left, and I reset it up. However, after plugging the cables back in and turning it on, it is not detecting anything in the diskette drive. I tried reseating the cable multiple times, and I cleaned the pins with 99% electronics cleaner. I didn't want to open it up but I may have to All I did was unplug and replug the cables, that's it I have tried doing control+reset to access the terminal, to see if it would even remotely detect the drive, and It wouldn't Granted I am not familiar with prodos, and I only know like 2 commands
I have done the following:
Deep clean EVERYTHING with lab grade electronics cleaner
Cleaned the heads with windex
Swapped main board with both of drives
Cleaned both drives hub
Reseated every socketable chip (Press down)
Taken it to the bare minimum (Keyboard, motherboard, power supply, i/o controller)
Ran some commands in BASIC with control+reset to force it to boot from the drive
Reseated loose connectors
Tried about 20 disks
Disassembled the duodisk about 5-6 times
Cleaned diskette conecctors (I'm missing some things i did but this is all i remember for now)

I usually use this book (Apple II Plus/IIe Troubleshooting & Repair Guide) as a starting point in troubleshooting. Given how throughly you've gone through the system reseating items, you might have a component failure.