https://www.dell.com/community/Printers/B1265dfw-suddenly-won-t-scan-to-PC/m-p/6092522/highlight/false#M88290

I found a solution to use the scan.
It is necessary to use the application "Scanner" on Windows 10 it works perfectly

and my next printer will not be a Dell

How do you do this?   

When I use scanner through the control panel it won't allow save as pdf or the typical security options given through the scan assist.   

@Virusjae  the solution is to connect your printer via DHCP into your network or directly to your computer

and use the application in advance mode of dell and add a new printer with the ip and the 

Dell B1265dnf Laser MFP

BTW, I'm network connected, not USB.

The solution is to use the original software that came with the printer, my disk is dated April 2013, and the Scan Assistant software is ver 1.04.39 dated 2/20/13.  You have to uninstall all the printer software including scan assistant, uninstall the printer in devices, reboot to be safe.  Then reinstall with the original software.  Seems I had a newer ver 1.04.52 dated 12/18/14 - that's the one that did not work.  Figured it out as I had a laptop with the older version that continued to work.  It was NOT enough just to run the disk without uninstalling everything first, I tried that.  BTW, the version on Dell's web site is the newer one, setup has a date of 8/13/15.  Now I did not try uninstalling everything and reinstalling the new version - would be curious if that worked.  Also my system with the newer version worked fine up until a few weeks ago when a MS update occurred.  Would be curious if the new version works with an uninstall and reinstall.  Network connected, not USB.