like when i click the launcher.exe thing for skyrim,theres a popup and it basically says its been installed the wrong way ,and if you reinstall it you might fix it,but i tried to reinstall it a few times and it still says the same. i can play the game fine using the TESV.exe file ,but i cant access the launcher which means i cant change the settings,its on a windowed screen right now and its really tiny and i want to change it to full screen.

not to mention i cant use mods now. but anyways,does anyone know how i could fix this or do something else to change the settings without using the skyrim launcher?

What is the popup you speak of?

It'd be most helpful if you took a screenshot and asked a mod to post the link for you. As far as I'm aware, there is no popup for Skyrim that does what you're describing.