the reason i put that command in was because i tried it in an attempt to stop hl2.exe has stopped working. can u also put it in simpler terms? btw i have one of the best video cards on the market. (supports DirectX 11 i believe)
If your card has DX11 support, it retroactively supports DirectX 10 and all the prior editions as well. Can you give us your exact video card?
To remove the command line from your launch options and reset your DirectX Level:
1. Launch Steam and log into your profile with the game [TF2] in question
2. Access your Library panel to open up the games window
3. Right-Click TF2 from the list of games in your library
3a. click Properties
3b. Properties window will open. Towards the bottom will be a 'Launch Options' button - click it
4. when the new Launch Options window opens, completely remove the "-dxlevel 81" (which appears without quotes in the window) from the command line.
(optionally) 5. Enter a new command line to replace the missing command line and reset your DirectX level. The command line is: "-dxlevel 98" without the quotes. This will set it to DX10 levels, or at least as high as TF2 goes.
If you'd rather fix this in-game, you can also do it via console. I assume you have your console activated and know how to use it, right? Here's the steps you use to reset your dxlevel to 98:
1. launch TF2 - you do not need to actively enter a server, just have the game loaded. You can, but it's not necessary
2. Access the console (tilde: ~ or also known as "that squiggly thing on my keyboard" ;P)
3. type the following command line in console: mat_dxlevel 98
4. BAMF! You're done! Restart the TF2 client and game away