How can I fix a dead mother board?

I accidenatlly spilled some water on my laptop the other day and left it to dry for a few days. It then used to switch on fine but whenever I’d plug in the charger it would turn right off. Now, it wont even switch on and I think the mother board is fried. I have very important files on that computer. Any ideas on how to fix the motherboard or at least get the files out?