garageband
I made a bunch of songs in Garageband a few years ago, on my old MacBookPro (ended up with Mountain Lion, I believe). When I open them on my new computer (a MacBookAir running Yosemite) some of the instruments (it's usually the drum kits) are not available. It gives me this pop up:
How can I get those old instruments so that these old files can be played and edited again?
There are many third-party virtual keyboard instruments. Do a search at the kvraudio.com virtual instrument news site. Anything that is in Audio Unit (AU) format will work with GarageBand. Here is a search result I have prepared for you.
Popular products you might consider:
Anything by Native Instruments
Buying Apple Logic Express or Logic Studio will give you all the Apple Jam Pack sounds in one purchase, with many other features besides. Apple Logic Express and Logic Studio.
Finally, read Keyboard Magazine. They provide a lot of coverage and reviews of products in this category.
There are Vocal Effects in Garageband. Open Garageband and create a voice project:
Then go to the Info pane in the bottom right hand corner:
Under Real Instrument>Vocals, you will find all the effects you were looking for.
Best Answer
The 4th column, Purchased. If it is empty that ends that unless you used a different Apple ID.