a community of practitioners
You need to contact your state board. Warning, some have stringent requirements for renewing an expired license, up to requiring enrollment in a refresher course. Probably most will want you to complete the CEUs you missed during the 4 years.
As an additional info bit:
I had a friend who was an excellent massage therapist, but she let her license lapse a few years when she married a surgeon and thought she'd never practice again... but, things have a way of changing.
Even though she had previously practiced for many years, She had to go back to school because the state would not grandfather her into the new hours that had become a requirement during the time she let the license lapse.
I always suggest therapists keep the massage license renewed (or put it on inactive if that is an option), instead of letting it lapse, for just this reason noted above.
This sub-forum may also give you some information: County, State & Country Requirements, Legislation and Politics, and if you get some info that is new or is not there, please add it for others to refer to in the future. You can search that sub-form for "California" and read all of the related threads on your state. :)
I recall a friend talking about California using the Holistic Health Practitioner (HHP) certification as the one that is considered more "professional". Depending on where you are, and what all you still need to do to get going again, you may want to look into this option, if you don't already have it and they end up requiring more education.
This is from 2011 and my not even still be in effect, but may also help you head in another useful direction:
In regard to local registration /licensure in California - I want to make sure you know about the CAMTC option. CA is one of just a few states that still allows local (city or county) license regulation. This was problematic because it allowed schools to offer bare-bones training programs, that didn't prepare their students to work in many of the cities with higher hour requirements....not to mention the disservice it does to the industry to graduate under-prepared massage therapists. As a solution, cities got together and with ABMP's help, created the California Massage Therapy Council (CAMTC). The first thing to know about the CAMTC cert is that it is optional. Therapists who choose to comply with local regulation only have the right to do so in city's that allow it. However, the CAMTC certification provides a statewide registration that allows therapists to work anywhere in California. It overrides local city regulations. Because schools in CA have historically varied in their hourly requirements, the CAMTC is a tiered system, offering different pathways to certification or licensure, depending on the the level of training and practice the applicant has. You probably knew about this - but just wanted to make mention in the even anyone out there doesn't. To apply with the CAMTC, start online at www.CAMTC.org.