Depends on severity. Memory loss from a head injury will not return. Some patients may have retrograde amnesia (loss of memory for incidents preceding the trauma) and some may have memory loss for events during and following the trauma. Neither will return. However, subsequent memory is usually normal.
Varies with severity. The extent and duration of memory impairment vary depending on how severe the initial injury was. Mild injury usually produces temporary symptoms, while more severe cases with damaged brain tissue will cause permanent loss of function. Much will depend on the location of the damaged tissue.
Concussion. You probably suffered a concussion. With severe head trauma, diffuse axonal injury may lead to long lasting and sometimes subtle permanent cognitive impairment. Sometimes repeating a neuroimaging, like an mri, may be necessary. Stay in touch with your doctor so he could determine if further medical care is needed. Recovery may be slow and it may take up to three to six months in some cases.
Recovery cont for 2y. Depending on the type of injury, spontaneous recovery from head injury can occur for up to two years. Speech/cognitive therapy is helpful for 'exercising' the neural pathways and doing activities to rebuild cognitive skills.