I'm with jj...Know that saying "Winners never quit, and quitters never win"? That applies to most everything in life, and especially to this hobby. Perseverance, patience, and the ability to educate yourself are necessary to succeeding.
I'd read up on the outbreaks that caused your system to crash and find out how to remedy them and make sure you go back to having tip-top water quality. I'd invest in a very good filtration system, do some treatment of your water, and maybe look into natural biological filtration and a protein skimmer/UV filter.
Only once you're certain your tank is safe and your water quality is optimal would I re-introduce any livestock (fish), and make sure their transition is smooth. Drip-acclimate them and make sure that it's as stress-free as possible. Stress to a fish can cause many problems, some of which involve weakening of the immune system, making them more prone to disease.
I'd check things like your heating system, making sure your water is always stable between 75-79 degrees Fahrenheit, and making sure you have great water quality.
It's important to remember that when taking on this hobby we're attempting to artificially replicate the ocean in a little tank in our homes. It needs a lot of patience and attention to detail.
Hope this helps a bit! Never give up, I'm sure you'll do great
- Vic