Pictures would help, I think.
A bit about validation: an Amiga drive will lose validation if the system crashes/reboots/powers down while there'd data being written (and if you're unlucky, sometimes while being read). Normally, it resolves itself if you let it sit for a while. But it sounds like your issue might be a bit more serious.
DiskSalv is the premiere repair utility - do not, under any circumstances, use DiskDoctor which comes with 1.3 (it'll make things worse). If you haven't discovered it yet,
Aminet is a great resource. You can find a version of DiskSalv there.