Many pediatric brain and solid tumors have altered epigenetic landscapes, and altered DNA methylation. As such this study is a Phase I/Ib study of combined 5'Azacitidine with an escalating dose of carboplatin for all recurrent/refractory pediatric brain and solid tumors. The phase I component will establish with maximum tolerated dose of carboplatin with azacytidine. An expansion cohort will be recruited of up to 30 patients will follow consisting of 20 recurrent posterior fossa ependymoma and 10 recurrent supratentorial ependymoma.