I have a serious problem: I installed Ubuntu 14.04 on my computer by selecting the Replace Windows 7 option. During installation it deleted all my windows partitions: D:, E: and F:.
How can I recover my deleted partition data?
I read a post regarding recovering data using testdisk. But it recommends having an external hard drive with double the capacity of the existing hard drive. At present, I do not have such a hard drive. Is there any other way?
That is correct, you need another disk to store the recovered files that the software is able to find on the disk, because writing to the same disk would cause more technical difficulties in the recovery process by overwriting other data also should have been recovered.
With modern spinning disk hard drives the consensus is that what has been overwritten is lost. So the sectors which contained data that have been actually overwritten by the installation of a new operating system should be considered definitively lost, the other data might be recoverable.
You should always have more than one hard drive when handling different operating systems or performing non-reversible commands and also heed the warning messages and notices (there was at least one when you did that). You should also have verified backups, that is at least 3 copies of a file and you know that it has the content and consistency you need.
