How Do I Reconnect Wireless Mouse To Wireless Keyboard On Lenovo A7 Series?

According to the manual:

6.6 Wireless keyboard and mouse instructions
(Only some models are equipped with wireless keyboard and
mouse)
Before using the wireless keyboard and mouse, carefully read the configuration instructions in the Quick Reference poster. If you fail to connect the wireless
keyboard and mouse according to the steps shown in the Quick Reference poster, you may also connect using the instructions below.

Method 1:
1. After installing the batteries, turn on the power switches of the wireless keyboard and mouse.
2. Press the wireless connect buttons on the back of the keyboard and mouse. When the keyboard and mouse wireless indicator lights blink white, turn the
computer on immediately.
Note: If the wireless indicator lights stop blinking, press the connect buttons on the keyboard and mouse again.
3. After entering the system, press the wireless reset button on the back of the computer for over 6 seconds to search for wireless devices.
Note: The process of searching for wireless devices could take several minutes.
4. When the wireless mouse device is found, the driver will be installed automatically.
5. When the wireless keyboard device is found, enter the PIN code and press the Enter key to finish the pairing process.
6. Once the wireless connection has been successfully established, the wireless keyboard and mouse will work properly.

Method 2:
Notes:
• Before using the method below, logon to the system using a wired keyboard and mouse.
• If you want to install a new set of wireless keyboard and mouse, follow the steps below.
1. Using the wired keyboard and mouse to logon to the system.
2. Turn on the power switches of the wireless keyboard and mouse.
3. Press the wireless connect buttons on the back of the keyboard and mouse to make the indicator lights blink white.
Note: If the wireless indicator lights stop blinking, press the connect buttons on the keyboard and mouse again.
4. To open the Devices and Printers dialog box, go to Windows and click Start → Control Panel → Hardware and Sound. Press Add a device to pop-up a dialog box.
5. Select the Lenovo Bluetooth Mouse and click Next to establish the bluetooth connection.
6. Select the Lenovo Bluetooth keyboard and click Next. (Press Add a device icon if the dialog box is closed and press the connect button again.)
7. Enter the pairing code and press the Enter key to complete the bluetooth connection.