Corrupt files and lost data

I reconciled all accounts, created annual reports and backed up data in Sept 2020, but when going back in Oct/Nov the data had all been lost and nothing was showing post April 2020, even though it had been available all year. Going in this morning now all data has been lost back to 18/12/19!

We are due to renew this subscription in the next 30 days and I thought perhaps we could start fresh with the new subscription and only pull over files needed for historical reasons.

I had backed up to Dropbox, but will be backing up to google docs instead if that is suitable?

Most files now have a red x against them not a green tick, so I assume they are the corrupted files?

Can anyone advise which is the best course of action and possibly assist with a clean up of the files? I have attached

some screen shots of the backup files.

Many thanks in advance.