After Effect not starting after installing new graphics card

can you open up a new file alright?
it looks like it's starting up a cuda process, and having LOADS of trouble talking to it. Which makes sense, because AMD GPU's don't have cuda cores, that's an nvidia thing and they'd sue anyone else who had them. it might be freaking out because the last time you closed it, After effects was set to use an Nvidia driver, and you opened it up running an AMD GPU. I'll assume you already installed AMD's drivers for simplicity- otherwise this is your reminder.
If it's just a preferences or cache issue, this will fix it:

hold alt while you launch the program. (I forget if it's while you click launch or just after, but you hold it till the spash screen is on) This will erase user preferences. You can use ctrl-shift-alt to really just nuke all settings and caches to factory defaults. you can also uninstall and reinstall to see if that works. Adobe programs can do wonky stuff with files behind the scenes, a little like a trojan might, with using invisible characters or leaving files when uninstalled, so just reinstalling often does not do the trick for these things. if you uninstall, I would browse around the program and %appdata% files and delete the after effects folders I found. it'll come back when you reinstall, nice and clean. at least it did when I tried with CS6.

as I said, before, you can use your computer without a GPU if your CPU has an APU. (gee that's a lot of PU's.). You haven't shared what computer you're running is, so it's kinda hard to help... but if your motherboard or CPU have onboard graphics, it should be pretty simple to disable(or unplug) your GPU, restart your computer, and get into AE. AE won't be any slower for it, luckily.