Losing your job when holding a work visa like H-1B, L-1, or O-1 can create serious problems with your immigration status, since it is linked to your work. After the end date, you typically have an optional grace period lasting 60 days or until your authorized validity period ends, whichever is shorter, to act to keep lawful status. During this time frame, you may try to secure some new employment, thus allowing for your new employer to file a petition on your behalf, or you can apply in order to change your status to another eligible category, such as a dependent spouse (H-4), or a student (F-1), or even a visitor (B-2). If you are eligible, you may also apply for adjustment of status toward lawful permanent residency or request a Compelling Circumstances Employment Authorization Document (EAD) in particular situations, though this does not grant a new nonimmigrant status. If absolutely no action is actually taken within that grace period, you are expected to leave the U.S. to avoid potentially violating immigration laws, as overstaying can affect future visa applications along with entry into the U.S. Given all the complexities involved, refer to the USCIS page for further clarification.