"unrecovered read error" means that the drive couldn't read the disc. Either the drive or the disc has a problem. If you are lucky, trying again a few times or cleaning the disc works.
When dumping wii games to a sd card, you get several files that you need to combine, before you can play them in Dolphin. I always use the windows built-in command line version for that:
https://support.microsoft.com/en-us/kb/71161
(open cmd, type copy /b file1.iso + file2.iso game.iso)
You might want Dolphin calculate the md5 checksum of your isos after that. Just google the md5, and you'll find out if you have a proper dump most of the time. SD card support on wii is a bit dodgy sometimes.
When dumping wii games to a sd card, you get several files that you need to combine, before you can play them in Dolphin. I always use the windows built-in command line version for that:
https://support.microsoft.com/en-us/kb/71161
(open cmd, type copy /b file1.iso + file2.iso game.iso)
You might want Dolphin calculate the md5 checksum of your isos after that. Just google the md5, and you'll find out if you have a proper dump most of the time. SD card support on wii is a bit dodgy sometimes.