Cannot restore from back up

I am sure this has been asked but googling has not provided an answer that I can understand - and I would rather run over my phone than pay $29 to ask why I can't do something that should be so simple. Yes, sorry, having a really bad day that resulted in accidentally erasing some text messages. Of course, the only way that i know to get them back is to restore from a backup. And I backed up last night - but I can't restore from a backup because apparently I do not have enough space. I am not technical and I cannot understand how that is possible - a back up should wipe out what you have and put back what you had - why can't I do this? And of course I don't have space when my stupid "other" folder is hogging 5 gb's and I can't for the life of me understand how to get rid of whatever is in there.

Any help would be appreciated - do I just erase everything on my phone, then restore from a back up? I'm so frustrated over this - I just want the texts back.

Thank you