I've just bought a transcend 530 8GB pen-drive. I was trying to make it bootable using ubuntu startup disk creator. I've selected usb flash drive as first boot device but it isn't detecting anything.
I've done it the same way before using different pendrive(which i lost). I've also tried Unetbootin to create bootable USB but got same result. What should i do now? is it a problem with manufacturer?

Is there a possibility that the process of creating the bootable usb drive did not complete succesfully? Have you tried on a different usb stick? Have you tried this usb drive in a different computer to see if it works?

Another thought, most modern Bios will provide a "Press F12 for bootup menu" or somehting similar which provides the option to select the boot device manually. It also gives you a nice listing of bootable devices. If it does, do you see your drive there?

if all else fails, download universal USB installer (free) and use that to write your downlaoded ISO of ubuntu onto your USB Stick.

I believe the Transcend 530 USB stick is basically the same thing as the Sandisk Cruzer. I have noticed that my Curzer is not detected either with any of the ISO writers. I think it has something to do with the partitioning of the stick for the sudo CDROM portion. Try using a generic el-cheapo stick and see if that works. It does for me.