My mom has dementia and on March 16th she could walk with help. On the 19th she lost all movement in upper and lower. Can that change fast?

When you write she "lost all movement", are you indicating that she couldn't move, i.e., was literally paralyzed, or did she lose the ability to move upper and lower legs w/o assistance?

If the two former possibilities, I'd call an orthopedist or neurologist STAT.   There could be nerve impairment or damage involved.  

I know it's hard to get through to doctors during this pandemic, so be diligent.

I hope it's not that serious, but it does frighten me.

Stroke is my first go to answer, having too much of that in our family. Can she talk to you as normal? Can she squeeze both hands?

Pain? A fall? Another existing health issue like Parkinsons or heart issues causing stiffness or fatigue? I've seen people just squeeze their eyes shut & physically refuse to move too.

See if you can get a Doctor appointment, even if it is by phone.

Why can't she move? Is it pain - in which case it might be a fall you didn't know about. Is it a sudden lack of strength? I hope that someone can comment on this possibility, as it puzzles me completely. Is it that she doesn't want to co-operate? A very recent post was from a guy who gave his father half-pound weights to lift in bed, for psychological reasons in being able to do something. If mother doesn't want to co-operate, you might find that she moves things around when no-one is watching. Perhaps worth a try.

It is possible. What is your mom's age? However, a physician can help rule out medical reasons. Other reasons could be she experienced a fall and no longer can. Again, a physician can help you determine if mental, physical, or both. They will test her right in the office if you get her to the right doctor after this virus thing is over. Also consider a specialist such as an neurologist.

In my mother's case, it was due to others not even attempting to help her walk as we did. It is much easier to throw her in a wheelchair and then throw her in a recliner where she sets for six hours or more straight laid out as if she is in her bed. No rolling out to get fresh air on nice days. No nothing.

It breaks my heart for my elders.

I wish your mom wellness.

What sort of dementia?

Changes can happen very fast, yes; but there will be a reason for it, which may or may not be directly related to her dementia.

I checked your profile - is it you who is 49, rather than your mother? How old is she?

How are you coping?