how do i fix? to normal

You have to do a system restore. If you don't have your original operating system CD then you have to do it manually. Reboot your computer and press F8 until the 'System Restore' option is available.

f8 didnt work.

what operating system do you use?

Depending on who made your computer the functions can range between f1-f12.
When your computer starts the first screen should have a few options.

Do you just mean that every program you open opens *with* notepad?
In windows, it lets you select what program you open file types with based on their file type code; the ".exe" from "diablo2.exe", or ".png" from "image1.png"
You can change that file type association as easily as right clicking on the icon of what you want to open, and selecting "open with..."
Then it should show the options for programs to open the file with, and let you choose if you always want to open the file with that program

i do that open with... then it brings me these:
adobe reader
esobi
internet explorer
microsoft picture
microsoft word
microsoft works
paint
windows media center
windows live photo gallery
microsoft word processer
Word pad
windows media player
windows photo viewer

or browse

What type of file was it before?
Save it in .ntl?

not a file.. every like program from like aim-teamviewr-diablo- any program all went to notepads so when i click on em jsut loads up notepads and says random letters... how do iget everything back to normal. all i did was want 1 thing to open with notepad that wasnt even a program then boom everything is all notepad.. i would s/s it but i cant load paint to s/s it!!!