There are a variety of reasons why a printer might start printing blank pages. Have a look here and you'll be back to printing as usual in no time.

If Microsoft Word prints blank pages when trying to print a mail merge document, it could be caused by a problematic printer driver or incorrect settings.

When I turn this printer it keeps on printing blank pages even though there are no jobs sent to the printer, and eventually it gets 13 Paper Jam error. I ...

Deactivate the Print Blank Printer Spreads check box in the Print Booklet dialog box to remove added blank pages from the output you print.