I've coached a good few writers through blocks of various levels of despair, and have a few hints and tricks that might help you.
First, find yourself some guided meditations which focus on self compassion. There are loads of them online, available for free, of varying lengths and types. Find some you like. Listen to at least one of them before you sit down to write every time, as this will help stop you being so hard on yourself, and telling yourself you can't do this. You can do it, and you can do it well. Trust me.
Next, try to write down a series of bullet points that outline what you want your dissertation to say. Don't worry about getting the wording of this right, or getting it down in the right order; just scribble out a few notes, as this is bound to change the more you get into it, and you don't need to get it perfect right up until the last moment. Just get it onto paper and be proud of yourself.
Once you've got all your points down, assemble them into a reasonable order that seems to flow in the right direction.
This is now your table of contents. Add a few subheadings if you can, but don't worry about that too much.
Well done! You're well on your way.
If you've got research to handother academic papers that back up what you're saying, or research you've carried outsummarise the important parts, very brieflya sentence or twothen paste those summaries underneath the appropriate headings.
Once again, look at all you've achieved and be proud of yourself.
By now you should have a decent framework to use to write your dissertation. Have a look at how many sections you've got to write, and then work out how many you'll have to write each day to finish a couple of days before the deadline. Then just write that many each day, making sure you use your guided meditations whenever the panic that you can't write takes you over. All you need is words on the page. They don't have to be perfect, just written.
Use the last two days to revise and correct and deepen.
You can do this. You really can.