Sword Plant

Sword Plant

Why are the leaves on my Sword plant turning clear???

I know i’ve seen this question posted before but I can’t find it now. Can anyone tell me why the leaves on my aquatic Sword plant are turning clear? They did this when I very first bought the plant and put it in the aquarium. Now it’s just the one plant in the aquarium cuz my betta died. Could it be becuase I took the water filter out and replaced the water 100%, so the water conditions changed??? Shoud I put the filter back in and continue to maintain the aquarium as if there was a fish in there? Any advice would be great. Thanks.
I bought this plant from petco and the tank sits right in front of my bedroom window so it gets natural sunlight.

When the conditions change too rapidly for the plants to easily adjust to, they “melt”, which is essentially dropping the majority of their older leaves so they can grow new, better adapted leaves. Crypts are infamous for this, but all plants will do it to some degree. Just pull out any dead leaves before they have a chance to rot, and let the Sword regrow.