Open up the DXi window in which you select the Instrument to use. Select Options and then Scan to find out whether DXi is still hiding somewhere. Alternatively, the driver may be VSTi which means adding the VSti to your range of VSTi Synths. Visit your list of synths from the above panel, select "Add VSTi Synth" and then navigate to the Program Folder of your player. Look for the progam name with an extension .dll, click to see whether or not PT will recognise the addition. If not, look for another .dll and try again. Sometimes, the installation of your player may hide the .dll in Windows > Program files > folder Steinberg.

I hope this helps.