The only way to retrieve data from a failed hard drive (and yours has definitely failed) is to send it to a data recovery service, and they charge a lot of money for doing that. You should have backed up the data to another hard drive or to DVD media. It seems like everybody has stopped bothering with backups judging by the number of similar posts I encounter. Unbelievable how much faith people seem to have in a single hard drive, like it's going to last forever.
As for using the hard drive from your old Acer I can't tell you for certain as you haven't provided any info about it., but generally speaking, if it physically fits in your Dell and the connectors are compatible, you can use it. But you won't be able to run the Windows installation that's on the old Acer drive. You'll have to wipe the drive then install Windows from scratch.