It can be frustrating when you're trying to rebuild your credit and you can't get approved for anything but there are some options that can help you get started. First, look at what debt you currently have and ways that you can begin paying that down. Contact your creditors and see what you can do to bring your accounts current and begin making monthly payments with a focus on paying on time each month. Next, you could look into a secured credit card. These cards typically require you to put some cash down and that cash becomes your credit limit, or sometimes it becomes a portion of your credit limit. This gives you an opportunity to establish your ability to pay on time which will go a long way towards rebuilding your score and making you more creditworthy to potential lenders.
Remember that rebuilding your credit is a marathon, not a sprint. Little changes will occur slowly over time but when you look back on where you started you'll be amazed at how much progress you can make over the course of a few months or a year.