It all depends what the ideas are going to be used for. I tend to always visualise ideas rather than as a story due to being artistic rather than a writer.

What are you looking to do with the stories or ideas you come up with? Write a short story, write a novel, paint a picture...?

It is near impossible to try and come up with any ideas or concepts from nothing. A good way to conceive ideas for anything is to brainstorm. Spider diagrams are a good way to do this. Start by just randomly writing down a list of anything that comes into your head, no matter have random or strange they may be. The write down the ones that interest you the most on a big piece of paper and then try to link these words to other related ideas and words using a spider diagram. Many ideas can come from this.

Another thing that can work is photography. Take a camera with you and go for a walk somewhere and just take pictures of anything and everything you see. Later when you get back home and look at the images, ideas will start to appear relating to some of them, or you may become interested in something contained in one of the pictures you didn't notice originally when you took it. Often some great ideas can come from random images.

Hope that helps in some way.

Other ideas might be to visit the library and instead of looking at novels and fiction, go to the non fiction area and start randomly looking at some of the books from any section. Non fiction contains everything in life and will spark many ideas.

Alternatively go to a comic book store and look through some graphic novels.

Or even just go to the park and sit on a bench for a while near a busy area. There are bound to be people around you can observe that may spark some ideas.