iPhoto has lost all my photo's

Dear All,

My iPhoto seems to have lost all my photo's and will no longer open. It does offer me the chance to open it holding down the option and command keys which I have done. My problem is there are too many options to re start iPhtoto and I don't know which one to select, options eg restore with thumnails, restore from back up etc.

I do not have any of the photo's saved to an external back up system and I do not know which option to choose.

Can any one help?

Many thanks

It is likely at this point that all of your photos are safe, but we need more info.
Mac specs
OS version
iPhoto version
Hard Drive size and remaining free space
Anything other related info (strange behavior before the problem, new software installed. Problem software you may be running such as MacKeeper or AntiVirus) etc

The above will be helpful in giving you specific instructions