Hammer not working

I open up SDK and (using hl2) click hammer, I get the egg timer next to the arrow mouse icon and then nothing happens

While using HL2 ep 2, no error message, basically, all the windows pop up for about 1-2 seconds, then it just closes.

I was using it yesterday, I have tried to reinstall it

Try verifying game cache, refresh SDK content, reset game configs and if that doesn’t work, delete clientregistry.blob.

Try opening up your Task Manager and closing out of the process.