Do the following simple steps,

::: insert your pendrive:::

1) Go to command prompt, type cmd and right click to cmd, and click "run as addministrator"

2) Type “ diskpart” , and Enterit will open another window and takes some time to load.

3)In new cmd window,type “list disk” and Enter (space between list and disk is must).It shows the list of disks.

4)type “select disk (Disk number of pendrive)” and Enter .for example, select disk 2(‘2’ represents disk number of bootable pendrive).

5)type “clean” and Enter

6)type “create partition primary” and Enter

7)type “active” and Enter

9)type “exit” and Enter, to close the window.

You will get your full capacity of pendrive.