Generally, if you still want to get back your inner data completely, you are supposed not to format this drive right now. The formatting process may erase your inner data.
The right thing you should do right now is to searching for "a proper drive data recovery tool" over the internet. There are many data recovery software available online. You should pay much attention to select a right one according to your own conditions. If you suspect, you could firstly try a hard drive recovery freeware here
to take a chance.
Edit: Before the successful data recovery, you should not write new data on this drive.
After this trouble, you should also learn a lesson to back up all your needed data all the time.