If your landlord sells your house can the new landlord raise your rent?

The new owner must abide by whatever agreement is in force. If there is a lease he cannot change any of the terms except by mutual agreement. If you are month-to-month he can only do this after giving you a proper written notice and anywhere from 30-90 days warning in advance, this allows you to either pay the new rental agreement, or look for another place to live. If this was not done, i'd recommend talking to a lawyer.