cant find a file!

I have a pdf file on my computer somewhere!
I cannot find it
I dont know how to look though

I know when i had xp, I could search for anything and anything with that name would come up
i could even search for .pdf and all pdf files would show up

now i have Windows 7
can someone explain to me how to search my whole computer for a file?
thank you

 

This will solve your search problems:
Everything Search Engine

I use the Portable version.
The 64 bit versions are only for use with 64 bit editions of Windows.
Be sure to check the Search drop down menu to see what filter is selected before searching.
I think the default is everything.

You can also try Winkey + F to start Windows search.