1) Get into a routine. If you've got yourself out of it, then ask yourself why, and try to get back into it. If you can't get into the routine again then
2) Take a break. Have a cup of tea, have a shower. Plan time for thinking
3) Read. Read how to write books, read methodology, re-read reviews, re-read research papers.
4) If you've hit a block and written less than say, 100 words today (see written kitten website,) then work on a different section
5) find downloads to listen to - Open University for example
6) Freewrite - a paragraph preferably at the same time each day, part of tip 1) routine
7) Have a comfortable (warm for example), well filed and tidy workspace.
8) Do your blog
9) Post problems online - twitter or facebook
10) celebrate writing 100 words or one paragraph - Rome wasn't built in a day. This is not perfection or a Nobel Peace Prize. It is only a PhD.
11) Do a MindMap.
12) Use aromatherapy - frankinscence oil
13) Hone your to-do list
14) Re-visit your training plan
15) Phone a friend
16) Do some filing
17) Write down your thoughts on bullet points
18) Be systematic in your thinking - draw a table
19) stimulate the 'learning' acupressure points: wrist, forehead, eyebrows, tummy
20) Revisit happy memories - has your supervisor ever given you praise? Go back to that time, place and go over what happened to get that.