I was typing on my computer and hit a key by mistake and now all of my programs are stretched out horizontally. How do I get them back to normal?

HAREENDRAN

Need some more information to answer your question!
However, first of all check the front panel settings of your monitor and / or connect another monitor to your computer if available. If without success, then check the display driver and make necessary changes to rectify the fault.See windows help to learn more.

chiru_mvgr

May be u have hit some display hotkeys like ctrl+alt+'some key' that support different dimensions of display.