Which coin i start mining, is it profitable, my budget is only 1000$.
I just want to take a start.
What your asking is on "Whattomine" dot com website, it ranks daily the most profitable coins to mine.
Thats the answer to your OP, its been ETH for the past year or more.
Now to address your budget, which is pathetic, and un-realistic.
Everything has its time, now is not. Six months ago I could buy an RTX-3070 for $500, and earn $10/day of Ethereum with that card. ( See you don't actually make any money in this game
Now that card is $1500, well over your budget. Now almost all GPU's on earth are un-available.
All GPU mining requires at least 6gb, but you need to buy more because right now ETH is at 4.6GB, and its growing, you don't want to be stuck with an obsolete drive.
Realistically the highest value mining with GPU is ETH, but your budget can't buy you a graphic card, there is none on the planet earth within your budget.
These days at the very least I would by a RTX-3060 with say 12gb, thats a long life, that card if you can find it is $1k, but your really need six to be in the game.
Just wait, all this shit will drop in price once ETH comes out with POS and mining is no longer profitable.
Beware also all the new RTX cards are crippled 'nerf'd' they say, its a real bad time to come into this 'game'