Here is the original item:
The potted geranium wilted
(A) from lack of
water on Terry's kitchen window
(B) while
the faucet dripped wastefully,
(C) staining
the porcelain sink with rust.
You wanted to do this:
The potted geranium wilted from lack of water on Terry's kitchen
window. While the faucet dripped wastefully,
staining the porcelain sink with rust.
The period after window creates a fragment. While the faucet dripped wastefully ... is a subordinate clause, which cannot stand alone as a complete sentence.
You might want to review the rules.