Ok. Let's try this:Try a System Restore to see if you can get your computer working again. You can do this in Safe Mode. If you can get it to work, please try below:
Make sure, your computer is set to obtain IP address automatically.
1. Go Start>Settings>Control Panel (Vista/7 users: Start>Control Panel)
2. Double click Network Connections (Vista/7 users: Network and Sharing Center)
3. Vista/7 users - From the list of tasks on the left, click Manage network connections.
4. For a wired network connection, right-click Local Area Connection, and then select Properties.
For a wireless network connection, right-click Wireless Network Connection, and then select Properties.
5. From the General tab (Vista/7 users: Networking tab), click Internet Protocol (TCP/IP), make sure it is checked, and then click Properties
6. Click Obtain an IP Address Automatically, and then click OK.