How can I make these computers share folders again?
Solution 1:
After fiddling with a whole bunch of junk
This needs to be defined. Sorry, but that's just how it is. Without knowing what you fiddled with and already tried, it's hard to know what to tell you that you may or may not have done. I mean, it could be something as simple as firewall settings. Silly, I know. But did you turn off the Windows firewalls on each computers? Does your AV suite come with it's own Firewall? Have you turned it off as well?
Both computers have internet access, which implies that the IP settings are correct for each, as well as the quality of the ethernet cables, the network adapters, and the router/modem. One computer kind of sees the other, but that's one way.
If you can't ping one computer from the other, while both are connected to the same router and getting internet access through it, then it most likely is a setting somewhere.
So, start going through connection tutorials. For example, this one at HowToGeek. Sure, it applies specifically to sharing files between a Windows 7 and Windows XP computer, but all you need to do is make sure both computers are properly set according to the Windows 7 settings explained and detailed in the article. Things like... making sure both computers are in the same workgroup... making sure network discovery is on at both machines... making sure that file and printer sharing is turned on at both computers... making sure that read/write access to the Public directories is available to both machines... try turning off password protection for both machines.... things you may or may not have done already, but the point is to double and triple check that each is done.
Try going into your router settings, and giving each computer a static internal IP address in the DHCP reservation table.
Here's another tutorial at AddictiveTips.com covering some of the same steps, and pointing out some other important details. It deals with wireless sharing, which I'm not sure, but I think partially applies here. You say that both networks have the same name... are they both considered Public Networks? You said you had to change the workgroup name and make them both the same. Did you triple check that it is spelled the same way on both machines, including capitalization?
In the end, again, you are going to have to detail what you've done here, so we can all follow along, and see if any of us can come up with something.