you might need to update the drivers for windows 7.
here are some other things you might try
make sure that the cd burner is getting enough power test all leads that are attached to the dvd burner including electical extensions and make sure they have a secure connection or just replace them there might be bad/faulty or
your drivers may have been corrupted or you might have a virus run your antivrus program
you might have to physically unplug the leads for this cd/dvd burner then plug them back in or
you might have to uninstall then reinstall your DVD/CD or uninstall the driver then reinstall for this device
click start control panel administrive tools,computer management,device manager scroll down cd dvd rom drives right click you can you can update driver,roll back driver,or
select properties general troubleshoot, select driver click to reinstall drivers click update driver or uninstall then reinstall
hope this helps
you only need to do this if you cant see your drive in my computer/windows explorer
if this does not fix the problem it might be a registry problem

Close all open programs

Click on Start, Run, and type regedit and press Enter
Click on the plus signs (+) next to the following folders

HKEY_LOCAL_MACHINE

SYSTEM

CurrentControlSet

Control

Class

{4D36E965-E325-11CE-BFC1-08002BE10318}

This folder is the DVD/CD-ROM Drive Class Description in the registry. Look for any of the following names in the right hand column.

Upper Filters

Lower Filters

Upper Filters.bak

Lower Filters.bak

If any of the above keys shown in step 4 are listed, right-click on them and choose Delete
After deleting the keys, close the registry editor
Reboot your computer
Open My Computer and check to see if your CD or DVD drives have returned. You may also want to open Device Manager and verify that the yellow exclamation and error code on the CD or DVD drive is gone.

hope this helps