People often find themselves feeling "trapped" in life, when, in reality, they just need to learn how to step back and analyze the situation.
When you say "too far into it," do you mean someone who has invested a lot in education and no longer wants to do that job? Or maybe someone who has been with a company too long and doesn't want to leave the company, or are making good money and can't afford to go elsewhere, or ????
You first need to ask yourself whether it is the job or the company that is the problem. Let's say it is the job. Now you need to ask, "why?" Is it boring? Are you no longer feeling challenged? Do you not like your co-workers? There are lots of variables, and, perhaps multiple reasons. It's nice if you can stay with the same company. Look around at other positions. Someone in sales can transfer to collections, or marketing. You are not stuck in one position.
You can stay with the same job at another company.
You can change jobs and companies. It all comes down to being able to show how your skills and experience relate to the position you are applying for. It's called "transferable skills."
If you are financially trapped, you make a plan. Start paying off the bills. Get rid of all those credit cards. Start living on less money, so you can prepare yourself for a paycut. Sometimes you have to make less for a while at a job that has a lot of potential.
If you want to give more particulars, I will be happy to try to be more specific. Basically, the key is being able to look around and see the opportunity, rather than just seeing a bunch of closed doors. If you keep knocking on those doors, sometimes they open.