Ideas for writing are not something we find, but rather cultivate. Cultivating, however, implies that we already have some "seeds". In other words, the key to having a wealth of writing ideas is to find those seeds, know how to cultivate them, and create a bountiful garden from which to pick one of many inspired ideas.
Since finding those seeds is a mental process, it shouldn't be a matter of long, laboring and tedious hunting and digging. Instead, it should be a matter of "mentally scanning" Tedious laboring is counter-productive to the creative process. Bringing a vast array of things into quick focus will usually result in at least a few ideas.
The mental scanning process should start inside and move outward. Begin by giving your mind a quick scan to see if you've missed any seeds that are already there. Have there been times when you've thought of an idea for writing but not acted on it? Are there things you'd like to say to "the world"? Do you know a better way to do something, or is there something you think other people don't understand as well they should? What things are important to you? What, in life, do you absolutely treasure? What bugs you? Scan your memory for people, things, or events that had impact on you.
Once you've finished scanning your mind for overlooked seeds, consider taking advantage of today's "great scanner of the world", the Internet. Go to writing sites and scan the categories in which you have interest writing. Scan titles within those categories. With the world of titles available there is usually something that will catch the eye.
If writing sites offer nothing scan national and local news sites. There may be something there that will trigger inspiration and cultivating.
Don't get bogged down by taking the time to do anything but quick scans. Don't read anything that doesn't immediately catch your eye as a possible idea for writing. Don't click on adds or links. The Internet will be there for other purposes later.
If you still haven't found anything that captures your creative instincts close down that browser window, put your hands in the air (or at least not on the keyboard), and step away from the computer. It's time to scan for some arresting ideas within your immediate surroundings.
Mentally scan things in your home, beginning with the room you're in and working outward. Think of things that mean something to you, projects you want to do or have done, things that bother you, or things are just interesting (or could potentially be). Don't overlook things you have in drawers, cabinets, or anywhere else. Move your mental scanning out to your neighborhood and town. Consider the latest issues or concerns. Mental scanning can work because the things that come to mind as you move from one place to the next are usually the things that most stand out to you.
If scanning "all of life" doesn't yield some immediate ideas it may be helpful to take a more in-depth look at some of the things you passed by during mental scanning. Essentially, this is a kind of "secondary scanning" to use if/when the "primary scanning" technique didn't yield any ideas.
Whether it's something as complex as a social issue on your mind or as simple as a loaf of bread, bring it into focus and think as many possible writing angles as you can. Something like a loaf of bread wouldn't seem to offer much to write about, but if you think about it a little more something so simple can offer a wealth of ideas: how it's made, how to save money buying it, ways to serve it, breads that offer the best nutrition, or how to make it. Think a little more, and ideas may include how well one or several bread companies are doing today, which countries make the most bread, or bread-making machines. More thinking may yield memories of the rolls your mother always served at Thanksgiving, which may lead to your memory of that Thanksgiving when your uncle had a heart attack, which may then lead you to decide to write about heart disease.
It can sound over-simplified to say that mental scanning for (sometimes seemingly meaningless) things usually results in ideas for writing, but that's because these ordinary things, alone, are not ideas/inspiration for writing. They are only the seeds, and you - with all your experiences, memories, curiosity, knowledge, emotions, thoughts, and whatever else you have to bring to writing - are the one who can cultivate and nurture those seeds into bountiful garden blooming with great ideas. As with most gardening, finding the seeds is not usually much of a problem. The trick is in knowing the steps it takes, and the climate required, for making them grow.