i see from your other posts you had issues with flashing, and installing Meego, Nitdroid etc. You migt want to search forum for how to repartition and reflash your N900 from scratch. Nitdroid, meego etc might have messed up your partitions, rootfs and more.
Hello Amr I know your case You need some steps to follow regarding your problem http://www.mobile4arab.com/vb/showthread.php?t=764328