Lost all Mail, Contacts, Calendar - Database crashed and wiped.

intermittent crashes.
checked mail_data.dat file and it was 2.92 GB
started to do what I used to do with pst files, which was rename the database
relaunch the program and copy over recent mail from the old database along with contacts etc to the new blank database that is automatically created except that didn’t happen…
emclient relaunched but then immediately crashed and now won’t launch again.
plus the mail_data.dat file has gone from 2.92gb to 1kb.
oh god, the last 12 months of email and contacts lost.

Actually you cannot copy various database files into another database folder. eM Client is now reading data from the newly created database where of course mail_data.dat has only 1kB. If you want to save your data, rename current database folder to e.g. eM Client 2, run eM Client with the original database and export the data (contacts, mails, events) out from eM Client. Afterwards, you can import them to the new database.