If the text bar is empty, you may had changed either the game files somehow(plugins, mods) or added addons that requires secured mod disabled. in order for some of these things work in-game, they automatically block secured servers to avoid VAC ban. here are a few things you can do:
-Check game's integrity files (if there's something wrong, steam will fix it)
- Disable all addons
-Reinstall l4d2
-Do the opposite and add "-secure" in the launch options (instructions above)
-Create a desktop shortcut and start the game from there.
If all of these options doesn't work, you should reinstall steam itself as a last attempt.

my launch options are empty. So now what?

My says launch options but in the text bar there’s nothing at all but it still says insecure is still in the text bar

wasnt even even there -rep

yo victor it is working so i had no issue if you write -secure it works for me and i appericated you victor and thanks for help!!!

lol

i took that out and im sorry that i said it was more helpfull i didnt mean it in a mean way i just love -lv and i only play vs so i needed to fix it

maybe, but if you have both -secure and -insecure at the same time, it won't work either way.

omg ty for the guy who said write -secure it worked more helpfull then this ty ty ty

hey write -secure