For organic and organometallic compounds (in general, for any structure containing some carbon atoms), you can usually get the structure from the Cambridge Crystallographic Database.  Without having a paid subscription, they will still allow you to download a few structures at a time from the database.  Here is the link:   https://summary.ccdc.cam.ac.uk/structure-summary-form

Then, you can get the free program "Mercury" from them which will take any set of single crystal data and calculate PXRD.  

So by doing a search for crystal structure of benzoquinone, I found the DOI for a paper, used the search page above and got this page where I can download the gif file.  https://summary.ccdc.cam.ac.uk/structure-summary?doi=doi%3A10.1107%2FS0567740878004707

Then, I use Mercury to convert to PXRD.  This is better because now you can zoom in on the data and analyze it more closely than, say, for a pdf of the pattern.   

Thank you sir for your response

The sites provided by Prof Joseph S Merola are very intersted and useful.