My Brand-New Computer Lacks The Basic Ability to Do Anything Wi-Fi Related?

So, I got a brand new PC, a tower to be exact, I loved it, and it was working for the longest time, around 2 weeks or so, all I had to do was delete the basic adware and data miners that are put on a basic windows OS copy, like Wild Tangent games. Now, this computer was pretty expensive, around $800, and so I get all my games from Steam on the computer, and I'm fine, playing Garry's Mod and TF2. I would also like to note that upon first getting the computer it refused to download Minecraft, I had to download the technic launcher and play vanilla through that. So, everything is fine, until one day we get a power surge, the computer to find but I have a limited wifi connection, I manage to make it not be limited but it does not work properly, it can't load webpages, play on game servers, Skype is unusable, etc. I've tried unplugging it while holding the power button or whatever that trick is, I've reset the modem numerous times, I've had my Dad come in and attempt to fix it (He was an IT guy until recently), but we can't seem to locate the problem. I've tried so many "solutions" but none work, I've flushed my DNS, uses googles DNS, nothing works. For reference: 64x OS, Windows 8.1, tell me if you need more info, and please help me make my expensive computer worth the money once again!

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