path variable vanished

Trying to set up opengl sdk. Added “F:\premake4” to environt-variables.
With sdk libraries present in “F:\glsdk_0.5.0” I navigate in the command-prompt
to the library. Executes
premake4 vs2008
premake4 not recognized as a command …

A first change of ‘path’ … it did not stick
a second, the added path was present after execution, but still erroroneous
Made a new intrance: “PATH” and added the value “F:\premake4” to it.
Error still applies

Return to environment-variables
The original “path” - variable [non-capital letters] with system-values are gone

… never mind getting glsdk working
should anyone have a standard set of path-variables (for win7 64bit) then please make a copy/paste so I can recover the functionallity of my pc ;o/