How do I get the old sticky notes back?

I haven't tried this but here's a possible solution: http://www.winhelponline.com/blog/get-classic-sticky-notes-windows-10-anniversary/

If you’re not going to use the new features (Cortana integration, Ink) of the modern Sticky Notes app, you can get the classic desktop version (StickNot.exe) after upgrading to the Windows 10 anniversary update (v1607) build.

If the C:\Windows.old…Windows\System32 directory is still intact, simply copy “StikyNot.exe” to your Windows\System32 folder and create a shortcut to it on your desktop. Also, make sure you copy StikyNot.exe.mui file from “Windows\System32\en-US” folder (for English language version of Windows), and place it in the same path in the target computer. The program still works in Windows 10 version 1607.

Another option would be to obtain the ISO image of 10586.494 (preferably) and extract the two files StikyNot.exe and StikyNot.exe.mui using 7-Zip or similar archive utility.

If none of those options are feasible, you may download it from this site.