Assuming you don't work with profiles, there's a folder Start Menu in the Windows Folder. It might contain a few shortcuts (you see in the upper part of the first column of the Start Menu) and it surely contains a folder Programs, which should contain the folders and shortcuts you don't see now. That's the go and search part (use Explorer). If there's no such Programs folder, make one?

With right click on taskbar, properties you can manage the folders and programs in Start/Programs. You might have to redo everything.

If the 'only' problem is that the folder accidentally got deleted, you'll be able to repair this more or less. In principle, it could be a symptom of another problem (viruses, hard disk problem). Let's hope that's not the case.