When I turn on my computer there is no boot menu to chose Windows XP or Ubuntu I don't know why. I can't access Windows XP and this Ubuntu 11.04 is slow on my computer & I don't want it. In Windows XP there is no in add/remove programs entry for Ubuntu, and my local disk where is installed Ubuntu is now smaller. I cannot recover that free space and I cannot delete that partition, so I need help.
You need to tell us how you installed Ubuntu. If you did a 'wubi' install 'inside' windows using the exe on the cd, then there Should be a entry for ubuntu in the add/remove program settings tool in windows.
If you booted a cd and did a normal install, then you would need to delete the ubuntu partitions, and reinstall the windows bootloader. Then resize or repartition the hard drives to get the space back where windows can use it.
Use TestDisk It has a boot disk option that will re-write the MBR http://www.cgsecurity.org/wiki/TestDisk_Download