Check in the /media/ directory. If they are present there, you can mount them wherever you see fit. Also ensure that you have the necessary drivers installed to view NTFS partitions; I do believe they are supplied with Ubuntu however.
*i had one hard disk of capacity 320 GB in my laptop. i seperated the drives to 50, 50, 100, 100.
*i installed windows in first 50 that is C drive. when i tried to install ubuntu in other drives it does not accept as they are basic drives. and for laptop i know that there should be one dynamic drive and others basic drives.
*so i installed ubuntu in C drive by allotting some 15 GB space. now i am able to mount or see the second 50GB drive only after booting through ubuntu.
*i need to know why or how the other 100 and 100 GB drives are not there in Ubuntu for mounting.
*In ubuntu the drives are visible like one is 250 around and one drive is 50 around that is second 50 GB. i hope you understand my problem.
Okay, so we're looking for partitions, that makes things a bit more interesting. How were they formatted? Pyroflea is right I've never seen Ubuntu have a problem with NTFS, but it doesn't hurt to ask. Any chance they were encrypted or hidden from inside Windows?
Also, I'm pretty sure gparted isn't included in the default installation of Ubuntu but might be helpful here. Try installing it, and see if it can find your partitions.