It's a littlebit hard from your description to understand what happened, exactly. What did you unplug? Where did you "put in" code?
Are you still getting the message that /tmp cannot be mounted?
What do you mean by "updating it with usb"?
What do you mean by "breaking the usb stick trying to get it to work".
I also do not understand "no is it possible to obtain one?" You can download iso images for your distro here:
But I guess this isn't your question?
Do you have access to another working computer that you can use to create a new live cd / usb?
I had a similar problem recently where I had added a bind mount to the /etc/fstab that was referring to a partition which was not mounted at boot time yet.
As teckk said your best shot is to boot into a live system. Then mount the partition that contains the operating system, and open the fstab.
If you are unsure what the problem could be post the fstab here. In any event, please post more specific descriptions of the error messages that you are getting rather than "something doesn't work"