I need to store and encrypt a password in a (preferably text) file, that I later need to be able to decrypt. The password is for another service that I use, and needs to be sent
Do not store the password as part of the code. Aside from the issues of decompilation and relying on security through obscurity, if you change the password you need to recompile and redistribution your application.
Store the password as a webservice or in a database that the application has access to. You're communicating with a service over the web, so you will be connected, after all.