Cannot get on the internet with new internal hard drive on my compaq desk top. Modem and router is working fine. Computer say connected bit it is not. Please help.

Replacing a hard drive usually involves reinstalling an operating system and drivers for all devices.

Did you...
1. Install correct chipset drivers?
2. Install correct network drivers?
3. Configure correct network IP settings?

If so, the router should be pingable from a command prompt with the command ping RouterIPAddress.