I feel lost with my master thesis When I sit and start writing my master thesis, I write the first couple lines, then I don't know what to write and get stuck.
I feel like I'm not creative enough for writing.
The questions are. How to get around this blockage? How to organize the ideas? How to stay focused? Is this think typical?
I have to assume that you have done the required research and are now just at the writing stage. 

This could be a lot of things. But one piece of advice is to not try to write it from the first word to the last. Work from an outline. Fill in the outline in such a way that it seems like a blurry picture becoming clearer and clearer. 

In other words, if you have some idea about methodology, work on that section for a bit. If there is something about the conclusion that comes to you, write that down. Go through whatever notes you have made and add ideas to appropriate sections as you go. 

Another technique is to use index cards effectively. Carry them around with you and add new cards or modify old ones as ideas come to you throughout the day. Index cards can be better than a notebook, since they can easily be rearranged and even discarded. As you mine the notes you have, write index cards for the ideas there. Rearrange as necessary. 

Ultimately a deck of index cards could, in some sense, represent the entire work. 

This isn't the only possible way to attack it, but a piecemeal approach might be able to help you avoid some forms of writer's block, such as being overwhelmed whenever you sit down. 

Of course, this method will require heavy editing for continuity as you get closer to the end. 



There is a more extreme method that was once mentioned to me by an English professor in an intensive writing course. He had a lot of contacts who were writers of various kinds. He mentioned one person whose method was to "make one page of progress" every day. The person would work until the current manuscript, including revisions, was one page longer than the day before. This results in a short story every three weeks or a novel every year. But, I suspect that it takes a certain sort of personality, somewhat obsessive, to manage that. And one page of progress is not the same as one page of writing. And it was creative writing he was speaking of, not scientific writing.