Most European countries no longer give out passports to descendants of citizens who have emigrated (indeed, just being born in a European country is not automatically a guarantee of citizenship and until recently many countries stripped expatriates of citizenship once they obtained citizenship of another country - you couldn't hold dual citizenship where one of them was Swedish, as late as 2000, and I know that is true for several other countries.)
The other answers telling you to get into a relationship with a citizen and move here, are true to a point, but I can tell you from experience that at least this countries government will be all up in your business checking it's a real relationship. Also, you need to have been in the relationship and apply for residency first before moving here, the application normally has to be done from your home country.
The easiest way is to get a job here, get yourself sponsored with a work visa, and look for a permanent job (or permanent relationship) once you get here.
Also, don't forget that "Europe" is a whole lot of countries. The rules aren't the same everywhere, some places are tougher than others, but nearly all of them have a national immigration service website, in English, where you can look at the requirements to gain citizenship.
