# If your drive or partition is missing and you don't have access to it
# do the steps below to assign a letter to the missing partition and
# the drive or partition will be back without any issue or data loss.
# Type the steps one by one in command prompt and hit enter
# You shouldn't type the lines that begin with #
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# oepn diskpart
diskpart
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# list the partitions on the selected disk
list volume
# now this part is important. Now DISKPART is showing you a list of all
# volumes on your computer. look at the "Ltr" column and see if all of the
# volumes have a letter( like E,F,G,...). if there is a volume that doesn't
# have a letter (if the Ltr cell is empty) that volume might be the parition
# that has disappeared from your computer so we'll assign a letter to it.
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# lets say for example volume 0 doesn't have a letter. first we select it:
select volume 0
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# and finally assign the letter you want to it
assign letter=D
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# Done, now exit.
exit
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# Now look in your file explorer to see if the disapeared partition is back