Black Mesa playing very dark

After the most laborious sign up procedure ever, even though I logged in with Steam, I’m finally here so I do hope someone can help me out.
For no apparent reason my game play has gone really dark. I’ve reinstalled the video display files and that hasn’t made any difference.
On a forum I was told to enter into the console MAT_HDR_LEVEL2 and also
MAT_TONEMAPPING_OCCLUSION_USE_STENCIL1
This did work the first time I used it but next time I played the game it was back to being dark. It loads ok, but in the first few seconds of gameplay it gradually goes dark to the point I can’t see to play at all.
Someone suggested I download all game files again but that’s using tons of bandwidth so that’s out. I have done the check of files though and it said one file was bad or something and was replaced. However still no joy after that.
I’d love to be able to figure out what the heck is wrong, anyone got any suggestions?

You have the overdark glitch. Restart your computer and:

To Fix The Over Darkening Issue
Type the following two commands into the console

mat_hdr_level 2
mat_tonemapping_occlusion_use_stencil 1

While I hate to trouble you with more of that laborious mouse clicking and key pressing, can you provide us your sys specs, GPU driver, etc? Y’know, the basics. Also was the game working fine previously? If so, how long ago?

Also you said the console commands worked, why not just put them in your autoexec and be done with it?

Founded in 2004, Leakfree.org became one of the first online communities dedicated to Valve’s Source engine development. It is more famously known for the formation of Black Mesa: Source under the 'Leakfree Modification Team' handle in September 2004.