Don't target Faralda - Target the rune on the ground (it looks like an eye) behind her.
If you do it correctly, it will light up.
So, I'm pretty sure she's not dead.
Unless you've already completed the Restoration Ritual Spell Quest (and gotten the two highest level spells from her), she should be flagged as Essential. That is to say, she should be unkillable. I know that I've been trying to for the past 10 minutes, and while she goes to her knees occasionally, she JUST. WILL. NOT. DIE.
So, what this means is one of two things. Either you've been hit by yet another famous Elder Scrolls Bug, and she's fallen through the world or otherwise despawned. While this is not impossible, I'd characterize it as pretty unlikely.
More likely, is the fact that she, and all the other college mages, wander around pretty constantly, and don't really keep to a 'schedule' the way most NPC's do. I once went weeks in game without being able to track down the Illusion trainer, for example. There are two unowned beds in the Tower of Countenance. They don't belong to anyone. It's not the bed that used to be Collete's.
As to where else you can get high level Restoration Spells, you'll find them randomly as leveled loot as you adventure - especially in Necromancer and Vampire lairs - though you'll never be able to gain access to the final two spells without completing the Ritual Spell quest, for which Collette is required.
Best Answer
tl;dr - Use Console (on PC) or Reload, get rid of the dragon, then talk to Faralda.
According to this list of bugs:
If you're on PC you can use the console command:
This will set the First Lessons quest to the objective where you have cast the required spell and must speak to Mirabelle Ervine, the Master Wizard.
If you're not on PC there seems to be no clear solution. I would recommend reloading a previous save (as soon as possible before the dragon appeared) then hang around Winterhold to see if the dragon attacks this time. If it does then kill it, then attempt to talk to Faralda. Don't talk to Faralda at all until the dragon is dead or doesn't seem to be arriving at all.
The trigger for the bug seems to be the following events:
Basically you want to avoid having points 1 and 2 run in that order - preferably the reverse.