You need to get hopeless teeth removed, rest can be repaired with or without RCT. Once done, all remaining teeth can be covered with a cap/crown and gaps can be restored with bridge wherever suitable. By following this your problem will be resolved permanently for rest of your life.
you can get either fillings done ..if no pain in them..but thats not permanent as there are chances of fracture ... you can get full coverage crowns done or else .. veneers or laminates .... only after root canal treatment in them ..as they were broken at 10 year of age ...
An x ray of the concerned tooth will be good to know if RCT is required or not. Once it will be clear, then you have multiple options like composite, veneers, laminates, crown. Cost varies place to place and type of treatment you choose. Cheapest treatment will cost you around 2 k to 3k with RCT and around 1k without RCT. At your place (delhi-NCR )the minimum cost would be higher for obvious reasons.
Get scaling and polishing (teeth cleaning) done by a dentist (to cure the problem from its root!). The scaliness on your teeth might also call for some esthetic treatment options (like veneers, laminates or plain composites!). Home remedies of whitening teeth include applying a mixture of baking soda and crushed strawberries to your tooth surfaces for a few minutes and then properly rinsing your mouth with water. Can be done once a day for a couple of days till you achieve your desired results.