Best course of action for missing files?

[Borris_Squad]

I had a lot of content, from various places. But I did not use all of it. But after upgrading my PC i have lost a lot of content over time. I don't really know what to do. Or how I could begin finding my content again.

[IMG]https://image.prntscr.com/image/lKAiK4PPT1q0yOOgcENIPw.png[/IMG]

I'm not sure if anyone knows where these models/materials may have came from;

models/props_windows/window_urban_sash_48_88_full.mdl
BRICK/BRICK_EXT_08

They seem to be the only missing things. I think they are from a source game? But I only have CSS, CSGO and Gmod installed. I have every half life and left for dead. Any help would be appreciated. If it helps; below are images of what should be there.

[IMG]https://steamuserimages-a.akamaihd.net/ugc/861737390172730537/ACADA9C91C35BEA0359BAC12052AE4B8F6D86E2B/[/IMG]

Thanks. It means a lot!

[KingPommes]

Might be some black Mesa stuff.

[Borris_Squad]

[QUOTE=KingPommes;53000140]Might be some black Mesa stuff.[/QUOTE]

I never touched Black Mesa. I'm not even 100% sure what that is.

[editline]23rd December 2017[/editline]

I mounted L4D2. They were from that game. -

[taz0]

Black mesa is the original Hal life story but with way beter graphics and its on sale at £3.75 go buy it you don't know what your missing :)

[Borris_Squad]

[QUOTE=taz0;53002021]Black mesa is the original Hal life story but with way beter graphics and its on sale at £3.75 go buy it you don't know what your missing :)[/QUOTE]

Will probably consider it.