Updating EM client resulted in me losing all my e-mails and contacts list. Is it possibe to retrieve?

Depends on which versions you updated from/to.

If you move from 6 to 7, you will be prompted to import the version 6 database. If you don’t do that, your local folder data will not be there. You can import it at a later time by going to Menu > File > Import > eM Client version 6.

With other updates, like from 7.x to 7.x the data will still be there. Unless you uninstalled and deleted the database, or you changed the database location.