problem follow this below steps :
# First connect your pen drive or memory cared
# Then go command prompt.
# Then type diskpart and hit Enter button.
# Then type list disk command and hit enter button.
# Then give you Disk number and hit enter button.
# Then type clean and hit enter
# type create partition primary and hit enter button.
Now you go to the my computer and select the pen drive and Format it and it will show full space of pen drive.