If you are holder of a Latvian Non Citizen's passport you can travel to Sweden for visits. If you wish to work or study in Sweden, you need to apply for a permit at Swedish Migration Agency.
The Swedish Migration Agency does not accept Latvian Non Citizen's passports. They require that you show an EU residence permit card. You can apply for such a card at The Office of Citizenship and Migration Affairs in Latvia.
As the application process at the Swedish Migration Agency is a long procedure for non EU citizens, it is recommended that you apply for naturalisation in Latvia which will provide you the opportunity to work and reside more freely within the Schengen area.