Only Have One Central Incisor... What to Do? (photo)

Without question, your best option would be to get braces to create a space large enough to allow room for your unerupted tooth.  Once the space is created an oral surgeon can expose the tooth allowing the orthodontist to move the tooth into the correct position.   This would give you the most aesthetic result long term.  Good luck.  

The previous orthodontic work appears incomplete.  It would be best to see an orthodontist and a cosmetic dentist to create a plan to do as previously advised. Any "short term fixes" would need to be fixed after the ortho is complete, so you would need to decide if it is worth the added expense.

these cases can be challenging and they require a team that have experience in them. today with the advent of implant dentistry and the availability of different dental implant diameter, thise cases can be done much easier. yfrom what i see in your pictures, you are having a space problem. the first step is an orthodontic evaluation to see if they can recreate space for you, based on that, the treatment modality can be either regular restorative by having veneers especially if spaces can not be made, andif you can have a space, than dental implant should be considered. 

It appears you still have crowding issues as well as a posterior crossbite on the left side. Depending on your age palatal expansion will open up space to bring the central tooth into the arch. Then cosmetic dentistry can reshape both centrals as needed. There are "quick fix" options available like 'snap on smile' for short term results as well.

I highly recommend you get braces and do exactly what they told you at the orthodontist.  BUT  you can do something temporarily with some cosmetic tricks( for the time being). You could have a dentist who is very cosmetic oriented, reshape 9 a bit -bulid out your lateral 7 to match 9 as much as possible to look like the missing front tooth and get a little more balance until you can wear braces!  Have a cosmetic dentist do a wax up appointment to try it-Good luck-