blogsearch does not function properly, I guess

I searched through the forums but just could not get a clue to solve my problem. There has been one issue discussed concering character encoding in sql database. I tried to switch encoding several times but it did not help me out.

When I am searching my blog via the searchbox, for example I put in “Französisch” (german for french) as well as lower case, or some other words, I get an empty searchresults-page shown. But I “do” have blogentries that include those words, like french in german… I went to the archives and searched for the article by hand, just because I wanted to link it from a newer entry I was going to write. I whonder when and why this happened? I knew times when I was shown results for those articles and searchwords.

I moved my webspaceprovider and domainhoster last year in December. I manually saved the database and re-installed it at my new webhosters webspace. Might it be, that only articles I have written beyond December are searchable because of some issues concerning the older database entries? Perhaps someone has a hint in which direction I can move to resolve the problem.