Cydia wont let me download on my iphone?

-I dont know why, but now cydia wont let me download anything. No games, themes, tweaks, or anything. Usually when i choose to install something it will take me to another page and have me confirm. But now, when i choose to install, it takes me to the page and says in red font, "cannot locate the file, try manually fixing the page." if someone has encountered this problem before or knows a solution, please let me know. Thank you