you may make a list of things your husband and your m-in-law have. File a complaint against them u/s 406 IPC. In case you just want things back and no other action, you may try through mediation centre with pre-litigation request

Depending upon territorial jurisdiction, you may contact the local police with a complaint; and on failure of police to take action, you may file a criminal complaint in the court of local Magistrate. You may also initiate appropriate proceedings under Domestic Violence Act.