You get back links for websites by working on them and asking other people to either put up links to your page or exchange links with your page. You can also buy the links. This becomes as a form of advertising. 

Another way is to write articles and get them published in the Article directories present in the World Wide Web. They generally include back links as a part of author’s credits.

Contact other webmaster. No one knows about your prime keywords on the anchor ext.  Very few people search for your domain name.  It is the anchor text that is used by the search engines to determine the relevancy of a link for a given search term., so it needs to be most common term that people will search on or when they are looking at site like yours.  

Google generally shows back links form pages pr4 or higher. So if the pages that linked to you have been slipped below 4.  This may explain why your back links have disappeared.

Methods to search the links is to search on your primary keywords and then go to each site in the top ten or twenty and see if there is “add url” page. You can also email the masters for link exchanging.

Summary

You get back links by requesting people to put your link on their page and in return you place their link on your website. You can also buy the paid links. Article submissions are a great source of one way links. One must define the proper terms and keywords in the search engine to find the releavant matches and links of their categories.