Hey Mona,
Before I lost a good majority of weight, I decided that weights could wait (haha).
So, instead of doing weights I would do a little more cardio so ended up doing about an hour and thirty minutes of cardio per day. It was very effective and, mixed with a healthy diet, I lost about 40 pounds in a few months.
My advice to you would be, try a few different forms of cardio, whether it be on the elliptical machine, stationary cycling, treadmill, or even forms of cardio outside of the gym.. Mix it up and try to go for at least an hour a day.
Good luck!
Ryan