If you say the top level is not working, you mean footswitch fs1 - fs4. These should always work because their mode cannot be changed between 'presets selection' and 'effect block switching'.

You can test the footswitches to see if they generally work:

1. Power your HD500 on while holding down the right navigation key. The test window will appear.

2. Now navigate down to the entry "BUTTONS" and confirm with the "ENTER" key.

3. Hit ALL footswitches and watch the screen, even the UP/DOWN, LOOPER, TAP - buttons. Each time you hit another footswitch the value will change from "0" to "1".

If all footswitches show "1" in the end, the hardware of your footswitches did not stop working. If they still show "0" your device has got a problem.

4. You can now power off and on again.

If it still won't work, although all footswitches showed "1" before, you can reinstall the firmware and do a global reset before you saved your presets over the editor to get sure your software is o.k.

Are all those switches on the same pcb?  Maybe the connector cable for those switches came loose.  That's the only other thing I could figure, and it would be an easy fix.