My computer got wet and wont turn on. How would I fix it?

Pray the motherboard isn’t damaged or you may be in for a replacement laptop since it’s a few years old, especially if it’s a common i5 model. Being from ~2010 and probably sold up until 2013 means used systems with identical or superior specs won’t be expensive. If the machine is beyond repair, look for a nice Haswell-Skylane business laptop - if you can find it, get a Win8 one unless you like Win10 that much.

Anyway, I really hope you removed the primary battery and didn’t do the worst possible move and turn the laptop on with water in the system - that has a nearly 100% kill rate but you can’t do much about that now so take it as a lesson learned.

What you need to do NOW is take the laptop apart down to the chassis (don’t worry about the screen), have a keyboard on order (near 100% fatality rate after water damage) and PROPERLY clean the boards to prevent more damage using this guide (although having an ultrasonic cleaner is preferable if you can get access to one). The keyboard is really up to you, but I’ve always factored it into the repair and ordered it before or after the cleanup because I’d rather not have it fail without warning. If I got a machine with the error you made, I’d order it once I was able to confirm it’s going to hold up and it still works.

As far as taking the laptop apart goes your best bet is to find a similar machine - it seems like the 8440p is as close as you’ll get but there’s a 1” screen differential that will mean paying special attention to how the laptop comes apart. If it isn’t as close of a match as it seems on paper, the service manual can be found from HP.