To dream that darkness comes upon you signifies failure in some work that you are attempting. Darkness is synonymous with ignorance, the subconscious, evil, death, and fear of the unknown. If the sun breaks through the darkness, then you will overcome your failures. If you feel safe in the dark, then it suggests that you like not knowing about certain things. As some might say, ignorance is bliss.
To dream that you cannot find someone in the darkness signifies that you need to keep your temper in check. You have the tendency to let your emotions get out of control and lose your temper.
To dream that you are lost in the darkness denotes feelings of desperation, depression, or insecurity.
To dream that you are groping around in the darkness symbolises that you have insufficient information to make a clear decision. Do your research and do not rush into making choices.