You need to look at the bigger picture here when making a decision. You didn't have collision insurance for what reason?
1. Is it because the monthly/bi-annual/annual expense was prohibitively expensive for you based on your current income? If so, you were driving a car that was way too nice and this is the hard way of finding that out. If you can't afford insurance, you need to be driving a $1,000-$2,000 car that is essentially disposable. If this is the case, can we also assume you don't have $5,000 lying around to get your car fixed?
2. Is it because your driving record is so bad that insurance is way too expensive? If so, kudos for picking a safe car since you were indeed more likely to crash. But also, same as #1, you need to be driving a beater until you get better at driving and your record improves. Hopefully in this case, you have more savings, but not necessarily.
3. It it because you did the cost-benefit analysis and figured you would save enough not having insurance that when you eventually crashed, you would be able to just throw the car away and buy a new one? If so, did the analysis work, or did you bank on driving crash free for 5 years and didn't make it that far? I.E. Do you still needed 4 more years of no-insurance-bill savings to buy a new car?
4. Is it something else completely different?
These questions may seem irrelevant to your current decision (fix or salvage), but I contend that the bigger picture is quite relevant for your immediate decision as well. For instance, if you are in situation 1 or 2 and don't have the repair money, the answer is salvage and buy a beater. If you are in another situation, that may not be the best choice.