Before you leave the office, make a “bookmark”  — a physical note that reminds you where to start when you get back to work. Then leave it on your chair or keyboard where you can’t miss it.

Here’s a sample from my desk:

1. SiM edits due at NOON ← this reminds me that I have a priority morning task (so I won’t start some other task and miss my deadline)
2. Pick up @ chapter 7 ← this tells me where to start (so I won’t waste time finding where I stopped yesterday)
3. Remember TPS cover ← this keeps the boss happy (I’ve forgotten several times and he’s starting to lose patience!)