@zahrahoda, Zahra Hoda , Make sure your device is charged before attempting reset and then powered off. Here are the instructions from the 1st link at the bottom, telling how to factory reset your device properly, link #2 is a video showing procedure. You can try this, hopefully it will solve your issue. Good luck.
I hope this helped you out, if so let me know by pressing the helpful button.
Follow the detailed instructions below on how to completely reset your RCA Android 7 Voyager (RCT6773W22) tablet.
Step 1. With your tablet off, press and hold the volume up (+) button and power button until you see the RCA splash screen with Nipper and Chipper. Release both buttons to reveal the Android bot on his back with a caution symbol above him.
Step 2. A new screen will appear asking you to use your volume up/down keys to move and the power button to select.
Step 3. Use the volume down (-) button to highlight "wipe data/factory reset." Once highlighted, select using the power button.
Step 4. A new screen will appear asking you to confirm your selection. Use your volume down (-) button to highlight "Yes -- delete all user data." Press the power button to select once highlighted.
Step 5. Once the tablet is finished wiping data, you may press the power button to select "reboot system now." This will restart your tablet.
Step 6. The system will begin to reboot and once again display the RCA logo with Nipper and Chipper. The next "Welcome" screen will prompt you to select your language of choice. Scroll through the options using your finger and press start when finished. Congratulations, you have successfully reset your RCA 7 Voyager tablet.