Hud Replaced by the Alphabet

I just decided to start up Garry’s Mod for a good ol’ NPC killing spree, when all of a sudden I realize that the game brought up was not Garry’s Mod, but Half Life 2! Not only that, but the text was messed up and the graphics greatly downgraded. I exit and start Gmod again only to discover that parts of the hud, including sprite graphics for weapons in the weapon selection lists, and the crosshair have been replaced with letters! What is going on here? Am I the only one getting this?

Show list of addons, tell us what you installed recently.

I haven’t installed anything since the last time I played. Also, it isn’t necessary - I just found out all source games I’ve played so far are having this problem.

[editline]19th August 2012[/editline]

UPDATE: I found out two possible solutions to the problem, yet both of them are stamped in my case. The first is to get into the resources folder of Half Life 2 and install the fonts. I’ve replaced my already existing fonts and it hasn’t worked. The second requires you delete the fonts in your fonts folder.

I can’t even see the fonts in the Fonts folder. If that’s even possible, how the hell did I go about “replacing” already existing ones?

[editline]19th August 2012[/editline]

FIXED: I had to restart my computer after replacing the nonexistent fonts. It’s all good.