Network adapter not detected, drivers not re-installing, HELP!

Hi guys,
I have a pc and i'm having some issues with my network adapter.
When i try and find model, it says "System Product Name Desktop"
I'm currently running Windows 7 64bit, Core i5 750 2.67GHz
Motherboard; ASUS P7P55D LE (Intel DMI Host Bridge)
Graphics; AMD Radeon R7 200 Series (2GB)
RAM; 8192MB DDR3 SDRAM 1330
LAN port; 1 x LAN(RJ45) port

BTW, I purchased this PC as a refurbished PC almost a year ago and never had this problem. It's always been connected to the internet and always updated??
Everything happened after we capped our internet, i booted my pc when our internet reset and this problem started.
It had been asleep (not properly turned off) the day before we capped the internet as i was downloading stuff, then it was turned off and turned back on we had this problem.

My network adapter is built into my motherboard so i don't have a separate chip.
I don't have wireless, it's only connects via Ethernet cable.
Tried a few cables, all are fine (we have another computer running off Ethernet cables to test, but switched it back to wireless and all cables are working)
Went into Device manager, there is NO network adapters showing up what so ever.
Downloaded all new drivers through ASUS's site, all work except the LAN driver, in which it's says "The realtek network controller was not found. if deep sleep mode is enabled please plug the cable"
I've been reading forums, i've turned my PC power settings to High performance and tried re-installing drivers, still the same thing.
I've gone into BIOS and gone into "Onboard Devices Configuration" which says -
"Realtak LAN - enabled"
"LAN boot ROM - disabled"
I enabled "LAN boot ROM" and nothing has changed..
I have disabled "Realtek LAN", rebooted then enabled, rebooted and still no luck.
My internet thing in my task manager says "Not connected, No connections available."
I have pulled the back off of my pc and checked the motherboard, looks fine.
I have checked the connection LAN port is not broken, all is fine.
When i troubleshoot the problem it says -
"Install a driver for your network adapter,
Windows did not detect a properly installed network adapter. If you have a network adapter, please re-install the driver"
Yet re-installing the driver fails still!
I've tried turning my computer off and unplugging the power cord, waiting 10-20 minutes and still nothing.
Have ran Intel (R) Driver update Utility 2.4 - doesn't work as no connection to the internet.
Have also ran Driver Talet, which says Network Adapter not found.

Hey there,That's where I've been getting my drivers from, I've been trying to install that exact driver and it comes up with ""The realtek network controller was not found. if deep sleep mode is enabled please plug the cable"

Its probably hiding down the bottom in problem devices.
Note >>UN<< plug the cable when installing the driver, and Turn sleep OFF
Have you got a restore point prior to your problem?

Roy

Hey guys, disk checker wouldn't run. I'd start to run it, and something would flick up and close immediately. Scan now came up with nothing wrong. I've checked my device manager, no unknown or problem devices at all. Also i am currently running my pc on high performance mode. All i can see on my device manager is as follows
Computer
Disk drivers
display adapters
DVD/CD-ROM drivers
Human interface devices
IDA ATA/ATAPI controllers
keyboards
mouse and other pointing devices
monitors
portable devices
ports
processors
sound, video and game controllers
system devices
universal serial bus controllers