You haven't provided sufficient information to begin to diagnose your problem. You also haven't said what steps you've already tried, so some of the following may simply duplicate your earlier efforts.
Have you restored the msconfig setting to "Normal startup"? If not, you should do that.
When you click on the network icon on your computer (near the time display), do you see your iPhone in the list of available networks?
Assuming that you do see your iPhone listed, do you get asked to enter a password or does the computer attempt to connect automatically (and then fail to connect)?
Open the Network and Sharing Center on your computer (click the network icon near the time display and select "Open Network and Sharing Center)
Click the link at the top left to "Manage wireless networks"
Find your iPhone in the list of wireless networks, select it, and click "Remove" then close the Network and Sharing Center.
Click the network icon near the time display, find your iPhone in the list of available networks, and click Connect. Carefully enter the password shown in your iPhone (Settings > Personal Hotspot > Wi-Fi password)
Does it connect?
If you still can't connect to your iPhone's Hotspot using wifi, can you connect using Bluetooth or when the iPhone is connected to the computer via USB?