I can be quite forgetful on a regular basis ! I suppose age has something to do with that :)
Forgetting or disremembering is the apparent loss or modification of information already encoded 
My brain must not encode right then.  I do have tricks to remember things though.
It reacts  with  a spontaneous or gradual process in which old memories are unable to be recalled from memory storage.
 Forgetting also helps to reconcile the storage of new information with old knowledge.
Forgetting
Forgetting or disremembering is the apparent loss or modification of information already encoded and stored in an individual's long-term memory. It is a spontaneous or gradual process in which old memories are unable to be recalled from memory storage. Forgetting also helps to reconcile the storage of new information with old knowledge. Problems with remembering, learning and retaining new information are a few of the most common complaints of older adults. Memory performance is usually related to the active functioning of three stages. These three stages are encoding,
a failure of memorial processes to encode information about unattended stimuli. It is important to note that the memory failure does not have to do with forgetting something that has been encoded by losing access to the memory of the stimulus from time of presentation to time of retrieval, rather that the failure is attributed to information not being encoded when the stimulus was present. It seems that inattentional blindness can be explained by both memory and perceptual failures because in experimental research participants may fail to report what was on display due to failures in encoded