Accidentally deleted everything from my dashboard

Hi, hope this hasn’t been discussed before as to not double post, but can’t find any other posts describing my scenario.

Bit of an embarrassing one, but as a noob I made the mistake of deleting everything from my dashboard. CSS, Robots, everything. All that’s left is the HTML file, which won’t update now. Is there anyway to get these deleted files back? I’m pretty sure I can create another CSS file, but have no idea how. Once again I’m a complete beginner.