Re installed Protools on new computer, not getting sound

[john8]

I was running Protools on a emachines ( Windows XP home) and the computer died ( had it for 5 years). I bought a new Dell and installed protools. When I pull up an old session from my external hard drive everything comes up fine, I hit play and no sound. The line is moving across the wave form and the green level lights are working. If I open up a new session and plug in a mic. I can hear the mic fine and turn up the volume but getting no signal on the screen. No green level lights on the mix window. If I het record I'm not getting a wave form just a line. I tried troubleshooting the audio drivers and the computer says its working. Can anyone please help. Sooo grateful if you can.

Thank you
John