You should be able to search for MSPAINT.EXE
when you find it, right-click, click on "send to" from the menu that pops up and choose the "Desktop (create shortcut)" option.
You should be able to drag the icon from the desktop and put it in the start menu where you found it previously.
Traditionally the Paint application has been located in
"C:\Program Files\Accessories\MSPAINT.EXE"
This is the procedure in previous versions of windows, at least.