ok, hard to help, but lets see, if these abilities are something like clairvoyance, its common for them to weaken with age. there are many theories behind this however, if this is something that runs in your family, try speaking with other family members and asking if/when anyone lost their abilities.
if it's something like 'i could cast any spell and now i can't' this could be a couple things, one you could be remembering things wrong from childhood, two, you're out of practice. go back and redo the basics [energy work, meditation, visualization, what is magick, how spells work] and start over from there.
could also be some type of trauma. i know of some empaths who got so hurt their subconscious mind shut off their abilities as a defense mechanism [personally i had a really bad experience astral projecting once and my body wouldn't allow me to project for some time out of fear] did something happen that scared or upset you involving these abilities, you might need to face this dark part and come to terms with it before trying again.
many people with 'natural born talent' don't try to improve, only to wake up one day and discover they aren't the best anymore and wonder how this happened. i don't know what exactly your lost abilities are, but it could just be you aren't using them as much as you once did.