Going back to work after a hiatus is difficult enough without consideration for how that employment gap looks on your resume. Unfortunately, it's probably one of the first things the hiring manager will notice. If you are lucky enough to land an interview, you'll likely be asked about the gap in your work history. But if competition for positions in your desired field is fierce, you may find yourself struggling to land the job interview in the first place. You need a job, and you want to get back into your former field, so what do you do to deal with the experience gap?
Consider the situation from the perspective of the hiring manager. You have a gap in your employment history, which is much more likely to be noticed and questioned than overlooked. That hiring manager is a busy person, because on top of regular duties, he or she has an open headcount to contend with. That headcount comes with job responsibilities, and somebody has to make sure they're still getting done while the position is open. Meanwhile, the manager must also advertise the position, read resumes, and conduct interviews. Unless competition is low and the employer desperate to fill the position, you are unlikely to receive a phone call asking for an explanation of the gap in your work history before your resume finds its way into the circular file under the desk.
Try addressing your experience gap in a cover letter. Focus on your motivation for returning to work, rather than the reason for the absence. This technique gives the hiring manager assurance that you won't leave again, which is a primary concern. You should touch on the explanation for the gap, but don't dwell on it. Explain that you have been out of the business for a period of time, briefly mention the reason, and then make it clear that you are ready to return to work and why. If the hiatus was due to personal or family illness, pregnancy, or other personal issue, you can say so without getting into private details, and then explain that the situation is resolved, and you're ready to return to work. If you left for reasons related to the employment itself, maybe because you thought something else would be more lucrative, more stable, or more enjoyable, explain that after trying something else, you have determined your former career to be the preferable option. If you lost your job and have struggled for a period of time to get back into the business, explain that the jobs you have worked in the meantime have been only for your livelihood, and that you prefer your former career.
Whatever your reasons for leaving, something is driving you back, and if you emphasize the rationale, the hiring manager will have some confidence that you're in it for the long haul. You also show sincere interest in the job itself, which tells the employer that you will be a motivated employee. That might just be enough to tip the scales in your favor when candidates are selected for interview. Good luck in that job search!