eth0 and wlan0 don't exist when I put ifconfig or iwconfig
 

I don't know what I did but I messed up.

I got an error saying cinnamon crashed and going into fallback mode and i had no internet connection when I opened my computer and ended up deleting cinnamon and rebooting.

Issue is when I did that after I logged in I got an error saying

unable to launch "cinnamon-session-cinnamon" X session---
"cinnamon-session-cinnamon" not found; falling back

And when I pressed okay I just got a black screen.

I looked up how to solve this and did ctrl alt f1 to get to a command line and tried redownloading cinnamon but i get a bunch of ign and error messaged saying failed to fetch and stuff. I'm guessing it's because previously I couldnt connect to my internet. Please help

You've not said what distro you are running so it is not possible to give you
a definitive answer on how to configure your network. However it can guess that
your system is using network-manager, so suggest you try nmtui.

I have a linux ubuntu computer

So it probably is using network-manager. Try nmtui.

Evo2.

I think Ubuntu uses the newer (and in my opinion mislabeled) "Predictable Interfaces Names" convention.

I'm pretty sure it does too, but not sure why that is relevant.

Edit: ahh, I see now that OP explicitly mentioned wlan0 and eth0.