My MacBook Pro will not start up- I had to erase the hard drive to partition it in advance of swapping it for a new ssd. I restored via internet recovery and from time machine but it won't start up. WHat steps can I take now?

I wanted to replace my hard drive with an ssd On my MacBook Pro mid 2012. I connected the ssd and initialised it. I resized the hard drive partition , but whne trying to clone it would not let me as I had not resized the partition correctly - it was too large. I could not resize it. I took a backup of the system using time machine to an external hard drive. THe only way I could resize the partition to below 480gb in order to clone to the ssd was to erase the hard drive. (maybe there is another way but I didn't know it.) I then tries to restore from time machine but it would not recognise it. I restored OS X via Internet recovery- I then was able to restore using time machine from my external hard drive. IT appeared to be successful - with the message saying the computer was ready to use. BUt it only shows the background wallpaper and nothing else. I restarted using the power switch and recovery. BUt it shows a symbol which I believe suggests it accept find the start up disk. FRom disk utility no options are available to me (all greyed out) and in start up disk although the HD is present when I chose it as start up I get a message to say it is not possible to change the start up disk. There are no other options In that box.

1. WHat can I do to restart the computer?.

2. My end aim is to swap the hd to the ssd- can I just swap this now and restore from my time machine back up?

I Have embarked on this after being convinced by the people selling the SSD that is was a straightforward process- I'm no expert And now need some help just to get back to a functioning laptop.