I know there are some threads that touch this but I feel I have done something uniquely stupid. hence the post and plea for help.

I am a beginner @ Linux.

So I have a PC with a HDD (hard disk drive) and SSD (solid state drive) It was running Linux Mint

/dev/sda1 - HDD Partition 1 - 2 TB (mounted this is /home
/dev/sda2 - HDD Partition 2 - 1 TB (separate back up drive, i was backing up files to this)
/dev/sdb1 - SSD Partition 1 - 100 GB (OS)
/dev/sdb2 - SSD Partition 2 - 20 GB  (Swap) 

The operating system was Linux Mint and was installed on the /dev/sdb1 i.e the solid state drive. I had partitioned off the sda into 2 TB and 1TB and presented the 2 TB as the /home to the OS.

Anyway last night I decided to make a return to Ubuntu via the path of Elementary OS. Everything went fine with the install until it stated that GRUB installed failed and this was a Fatal error (no kidding I said).

No I am stuck. I have definitely done something wrong and don't know what it is...

My biggest pain is the files on the /dev/sda2. I want to save these before I try something drastic like wiping off the /dev/sda completely.

So I have the following questions...

1. Can I use a liveCD USB to save these files ? I can see the /dev/sda2 but was unable to access the files in the liveCD
2. last not least ... how do I fix the main issue here. Why could the OS not install GRUB 2b... why is my SSD the /dev/sdb ... and not /dev/sda. Does that have something to do with it that my master boot record sits on the HDD /dev/sda and not /dev/sdb