No Microsoft programs after reformatting my computer

After reformatting my computer, I had to use microsoft excel for a project and found out that it was gone. Thus i checked my computer and there is not a microsoft programme like words or things like that. Do i need to reinstall the excel programme or something? I use windows vista home premium.
 
I'm not sure if your meaning of formatting is the same as mine but whenever you format a hard drive, you erase/wipe out everything on it including the operating system and all applications. You have to reinstall everything from scratch.
 
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