There is no calculator in my Accessories folder!

Click Start>Settings>Control panel
in control panel click "add remove software"
on the right side click add remove windows components, new window will
open
click accessories and utilities, new window will open
click accessories > select calculator if not selected
click ok on all window

that should do it

alternatively if u think u deleted the link in the accessories try this
click start >run> enter "calc"
click ok
it should open calculator

enjoy :)
sandy