Always triple check which drive you are about to format. It may sound dumb but there are some people (like me) who had to reinstall the whole os because of that.

I feel with you.
Once dd'ed the wrong drive destroying my second harddrive instead of flashing a CF-memorycard.
I could recover maybe 10% of the data, but luckily there was no really important stuff on it.
Lessons learned...

I always format only my c drive whenever it feels bloated with softwares, so that other data in other droves is untouched

If you accidentally format a drive (quick mode) you may try out "testdisk". It saved me a lot of times.

Reminding me of my first format...
Was learning how to operate my brothers 286 but I could only play with a piece of software he made specially for me... (was like 10)... One time, one of college colleagues of my bro told me that to play doom I had to write Format c:\... My brother only laughed... He didn't anymore when he lost one year of school work next day...

A bunch of years ago, a friend asked me to clean up his PC. It had two partitions, only C: had to be cleaned. So I did the following:
1-create a directory C:\Backup
2-explore each directory for documents and copy them to C:\Backup
3-copy C:\Backup to D:
4-FORMAT C:

I did all the steps. Then I realized I forgot to do #3.

My friend's father was a cardiologist and the documents were his patients' data. All gone.
And Internet wasn't a thing at that time. So no recovery tools.
My friend had to tell him what happened. I wasn't there, but I still feel ashamed for this.

Moral of the story: always check thrice what the hell are you doing.

My system shows USB as sda if it was connected at time of boot and My HDD as sdb

Rest of imagination is left up to the reader (Do it twice tho in different manners. It would the n be relatively more accurate)