help with my comp asap!!

Ok so my niece was messing with my computer and when i went to turn it on the screen format is sideways and i have to turn my head now and dont know how to change it back..

I am getting help regarding my other computer being locked tomorrow... but i need help with this computer ASAP... HELP HELP HELP... UGHHHH

CALL ME IF YOU CAN GUIDE ME ON HOW TO CHANGE IT.

XOXO
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