my Seagate 3 t harddrive is shown when I go to device manager but its shown asdestop scsi disk it didn't do that before also now my cdrom has not been showing in device manager
Would you please open Disk Management and check if the drive is recognized there and also what it says about it and the CD-ROM? Please post a screenshot (you can use imgur.com to upload the image). Basically it might be a matter of just assigning the drive a new letter, here's how to do it: How to change the drive letter assignment in Windows.
You could also try the drive with a different computer and a different cable to see if the same thing happens again.
Would you please open Disk Management and check if the drive is recognized there and also what it says about it and the CD-ROM? Please post a screenshot (you can use imgur.com to upload the image). Basically it might be a matter of just assigning the drive a new letter, here's how to do it: How to change the drive letter assignment in Windows.
You could also try the drive with a different computer and a different cable to see if the same thing happens again.