I had a dinner reservation, but the restaurant cancelled it for some reason.
ーI had a dinner reservation, but the restaurant cancelled it for some reason, so I had to rebook it.
「ディナーの予約をしていたが、なぜかレストランが予約をキャンセルしたので、再度予約した」
to have a reservation で「予約してある」
to cancel で「取り消す」
for some reason で「なぜか」
to rebook で「再予約する」
ご参考まで!