you will most likely need to do something like this.
if you don’t have other ways of fixing it…
stuff like this can happen during migrations, then running rsync again usually fixes it…
but i doubt you are in that group…
no worries tho, your node should be recoverable, first off you most likely want to do a
fsck / chkdsk
to ensure that the filesystem or disk isn’t corrupted, if that is good then you should proceed and follow the instructions in the post linked.
and if you want to be totally sure, give it a bit and let @Alexey weigh in
sadly corrupt databases happen, especially when operating using regular filesystems and single HDD setups.
and no need to worry about the downtime, your node can be offline for 12 days without much fuzz.