I have top level domain for my blogger but now I want to switch to wordpress as wordpress is much better in everything from blogger. My blogger blog has some baclinks to main page and also has deep links so is it safe to migrate to wp without any significant effect on rankings. As every link address will be changed while switching to wp. Except main domain. I am quite confused with it as I dont like dealing with this technical stuff, so please explain in simple language.

You could use mod rewrite to redirect the urls to the new wordpress site. You'll retain pagerank as long as you do it correctly.