a Few weeks ago, I installed a HUD for my TF2, and it completely destroyed it, so... I got an email from Steam Support and I will show it now. And if you got the same problem, try it yourself!:
Hello,

A staff member has replied to your question:

Hello Alfie,

Our steps aren't going to get the HUD working, we do not assist with 3rd party mods.

The following steps will remove your old TF2 installation and create a new one, but you will need to ensure you remove any 3rd party files before re-testing the issue:

Exit Steam entirely.

Browse to your Steam installation (Usually C:\Program Files(x86)\Steam\)

Rename the "steamapps" folder to "old_steamapps"

Re-launch Steam and re-install the game.

Once the installation is complete, test the issue.

If this resolves the issue, you may copy the new files into the "old_steamapps" folder and rename it to "steamapps" to restore your other games without re-downloading.

If the issue is not resolved, you can rename the folder back to avoid having to re-install other games.