I am sorry to hear about your problems but it reinforces the importance of regular backups preferably to external storage media.
What if instead of a memory glitch your disk drive or whole PC had failed? Then you would lose all Projects and all Media files too!
Apart from your GEDCOM only FH Backups, FH also keeps regular snapshots of your GEDCOM file for each Project.
So use the File > Backup/Restore > Revert to Snapshot… command and review the Snapshot Taken dates.
Choose the one that you think will be just before the failures occurred and click Revert to Snapshot…
You can repeat that process for different dates as often as you like until you get the best outcome.
Having got back to some state of normality please review your backup regime.
See FHUG Knowledge Base ~ Backup and Recovery:
That has specific advice for FH and general advice near the end about Making a Safe Backup to external storage media.