Hi what you are talking about comes under the general heading of software - ie programs which you use to do things.
MS Word is software which is used for word-processing. You can buy a copy of it separately, or it also comes as one part of MS Office, which also includes Excel, Outlook etc.
Most likely, as you say Word was working on your laptop before, it is still there - just hiding :-)
Two easy ways to find it :-
1) Press the Windows' key and scroll down the menu list - Word maybe lurking under Ms_Office
OR
2) Find a Word file using Explorer - they are generally ones with a doc or docx extension, eg MYdiary.doc - and double-click that file.