Plot hooks are always a sore subject for players and GMs alike. The GM wants players to want to advance the plot, but can't always find a way to entice everyone. Players (usually) want to advance the plot, but they want to stay true to their characters. The GM doesn't want to railroad the players, and the players don't want to abandon the GM's carefully planned storyline.
Players first: You've probably heard this advice before, but you should find a reason to want to do what you know the GM is hoping you'll do. In a fantasy setting, it may be that a rogue hopes to loot some mysterious ruins, a wizard hopes to find knowledge there, and a paladin wants to get rid of the evil that has taken up residence. Whatever their motives, you can find a way to make most characters want to go check out the ruins mentioned in local gossip. In a modern setting, one character may want to solve a crime because he hopes to get the reward, another may not like competition, still another may be afraid she'll be the next victim, and one might be afraid he'll be the next suspect (GMs can play into this one, too).
If you cannot think of a justifiable excuse to bite the plot hook, talk to your GM. Maybe this is the sort of plot that you'll have to pass on. Maybe it can be slightly tweaked. Maybe yor GM just needs a little help figuring out your party's motivations.
GMs: If players aren't biting into those juicy plot hooks, maybe you need to look at the characters' motivations. If you have self-interested characters, you aren't going to get them to help people without a reward. Likewise, if your characters are noble and benevolent, all the loot in the world won't get them to do things that aren't saving someone's day.
If you're having trouble with it, talk to the players. They can help you see their characers' motivations, and you can help them see how certain plots can fit into those. Eventually, you can reach a solid understanding and progress the plot.
If none of this works, you may need to look at your group dynamic. A party with conflicting goals is fun, but if those conflicts are too open, it's hard to work on the same things. And a group of players who can't cooperate may need to find different games. After all, even if you're all friends, there can be issues with playstyle. If you separate and move on, you can avoid tensions that might move well into the non-RP realm.