There is plenty of info out there about how to go about getting to Disk Cleanup (cleanmgr.exe). This is just a quick little batch file to restore it. You do have the option of installing the Desktop Experience features through Server Manager. I personally don't like that option because of the junk that comes with it. Try this out instead...
Copy and Paste into notepad, save as "AddDiskCleanup.bat"
xcopy "C:\Windows\winsxs\amd64_microsoft-windows-cleanmgr_31bf3856ad364e35_6.1.7600.16385_none_c9392808773cd7da\cleanmgr.exe" "%systemroot%\System32"
xcopy "C:\Windows\winsxs\amd64_microsoft-windows-cleanmgr.resources_31bf3856ad364e35_6.1.7600.16385_en-us_b9cb6194b257cc63\cleanmgr.exe.mui" "%systemroot%\System32\en-US"
From this point on you can simply go to start > run > cleanmgr.exe