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A quick search of anime girls in wheelchairs gave me Tegami Bachi (http://en.wikipedia.org/wiki/Tegami_Bachi)
. Not a lot of information on there and I haven't heard of this series myself, but the bad guys are big armoured insects (that could come from grubs?)
Im probably wrong but it cant hurt to suggest it:
The wheelchair girl and the other world where she can walk, etc all remind me of .hack//Sign (mainly the character Subaru.) Still, like I said, that doesnt match a lot of the description. Check it out on wikipedia and see if it rings a bell.
This sounds a lot like the French animated series "Clementine" to me. Clementine is an aviator's daughter who is paralyzed and confined to a wheelchair after her father's plane was attacked by a fire demon, named Malmoth. Clementine is protected by a "good fairy", Hemera ("Dawn/Day" in Greek), who visits her in dreams and transports her into various historical or fictional scenarios (Oliver Twist, Egypt at the time of Akhenaton, Hansel and Gretel in Germany, etc.) Malmoth's sidekicks are known as "les grouillants" (the creepers or crawlers) - they are temporarily given human form as villains in each episode (such as an evil doctor, a Machiavellian noblewoman, a corrupt inquisitor) and they try unsuccessfully to capture Clementine. In the final episode, set in Japan, Malmoth is defeated and Clementine wakes up able to walk again. (There's also a second season, which was much less well written, and I've only seen bits of it.)
The series was released (partly) in English as "Clementine's Enchanted Journey".
http://en.wikipedia.org/wiki/Cl%C3%A9mentine
This one has been bugging me for years, and I just can't figure it out. I believe the film was anime of somekind, and it involved an innocent girl who starts the film in a wheel chair. And there is some kind of evil thing that sits on a throne in some other place trying to destroy her. He has minions who makes out of grubs in a bowl near his thrown and tries to stop the girl from doing something, not sure what. There is also some kind of world change or something and the girl can walk in this other place. Any ideas?