I dont have dvd drive in my laptop how to install ios fro pendrive

?? The only IOS I know is an Apple operating system. Since this is a Windows XP forum, I don't understand. three questions. First, are you trying to do a complete OS install? If so, which OS? What OS is the machine currently running?

i was using win xp in Toshiba portage r100 i don't have DVD drive in my laptop i want to install OS how i can install os frm pen drive i don't have operating system plzzzzzzzzzzzz help

1) Contact Toshiba support. They can probably supply a recovery CD at the very least; maybe your machine came with a recovery partition and they can talk you through it.

2) If you have a bootable recovery CD, or a valid XP cd, there are ways to build a bootable pen driver but ONLY IF the pc supports booting from USB. heck, if it boots from USB, you could borrow a USB CD driver from someone.

So there are two steps. The first is to have recovery media: a recovery disc drom Toshiba or a good XP distro with a license. Once you have either of these, if you can't get your hands on a USB CD drive you need to build a bootable pen drive. This will require that you borrow a working computer to build the bootable media, using some tool like this: http://www.techtipsgeek.com/install-windows-from-usb-fl...
or one of the other techniques here (on Tom's) http://www.tomshardware.com/forum/50282-34-tutorial-ins...

Good luck