Server not working like before (Need assistance)

[Peroshio]

I have been running a tekkit server on my PC running windows 7 hooked up to the internet, and port forwarded for some time now. The port was correctly forwarded because I have had people on from all over the place including me (on my other computer). About a month after I got back from summer vacation I couldn't connect to the server, and it gave me that failed to connect error. Although, other people could connect to the server, and so could the PC that was running the server. This obviously means that this is a local problem on this computer (which as I should probably say is a mac >.> <.<). I have deleted all of the technic/tekkit files on the mac, and installed them. I still can not connect and it still gives me the same error, "Failed to connect". The only thing that I can think of is that the IPV4 of this mac is the same as the server. Can anyone point me in the right direction on what to do to solve this problem?

*Added notes*: I can also connect to other servers, and it is just my server that I can not connect to, but again, the port IS forwarded because other people from all over the US can still connect.

[theprolo]

Have you tried :localhost ?

[Peroshio]

Have you tried :localhost ?

No, but wouldn't that only work on the computer that was hosting the server? I'm trying to go on the server with another computer, but it gives me the error message of,"failed to connect." Other people can still get on, just that one computer can't