Click on the link below:
Click on the HPVUD50.zip link, this will take you to a page where you
can buy it for $2.99, download it IF you view about 8 ads (Just select
no thanks, or next ad) which is what I did. Or get a premium
Needless to say I have the file downloaded and if you had you email
open I would send it to you. It is 2.41 meg zip file and has the 720C
dll in it. So just select the button to view the ads and download it.
Once downloaded, unzip it into a directory, and add printer> local
(Dont detect) > Select I have disk and browse to the directory you
unzipped to. Then select the 720c and you should be good!
Another way is click add printer > NEXT> Local (Dont
automatically detect) Next> LPT1 (assuming it is not USB) >
Select HP in the left window, then select HP DeskJet 720C in the right
window. click Next> Next> Next> Next> Finish. Click OK, It
should now be printing a test page.
Sure this helps