In the NBA, if a player.....?

signs a two year contract, and plays the whole first year, but in the off-season, he gets injured that will sit them out for the next year, do they have to play the third year without changing anything in the contract?? And if they can go wherever they want the third year, even though they didn't play the second year, do they get their full salary for the second year?

In the NBA, if a player.....?nba rules

Even if a player has a season ending injury, he still gets paid, with no contract extension.

In the NBA, if a player.....?nba live ,nba teams

Why did you ask this question for basket ball and football???? Are you insane??? jk
Unlike some other sports leagues, the NBA's contracts are mostly guaranteed. This means a long term contract is binding regardless if a player is injured or waived (i.e. if a player gets cut, he has to be paid until his contract is over). And yes, at the end of the 2nd season, they're eligible for a new contract or contract extension.

There's a few instances where the player will not get paid in full.

Sometimes clauses in player's contracts that give a 'performance bonus' if they play in a certain number of games a season. So certain players may be penalized for sitting out half the season (usually a term set in contracts for players coming off major injuries or are known to be injury-prone). However, the majority of the contract is still guaranteed money and these clauses are rarely used.

Other times, there's specific conditions which will render the contract void. Like many NBA contracts have clauses ensuring the player does not participate in any dangerous activities such as sky diving or riding motorcycles. If a player in injured doing such activities, the player may not get paid the amount remaining on his contract. Jay Williams of the Bulls who got injured riding a motorcycle had his contract nullified (although the Bulls gave him a $3 million dollar buyout as a goodwill gesture).
he gets paid
well first understand. players get signed a two YEAR contract not a two SEASON contract. if he plays the first gets hurt the second and misses it well the team pays him the full ammount and his future with current team is questionable. they can keep him or let him go so he can be availble for other teams to pick him up.