Hi abdallah, welcome to the community!
There are two ways of removing the lock.
The first way you could try is logging into my Xperia or Android Device Manager with your google account (or Sony Entertainment Network account if using my Xperia). If it does locate the phone then you will be able to choose a new lock that overrides the current one and enter that into the handset.
If the phone is not able to be located then you will need to do a software repair on PC Companion or Bridge for MAC. Please note that this will delete all user data as the screen needs to be unlocked in order for data to be backed up.
Running the software repair on PC Companion:
1. Install and open PC Companion then select Support Zone.
2. Phone Software Update.
3. Start.
4. Repair Phone
5. Continue
6. Accept data removal
7. Next
8. Wait for prepare
9. Select Phone
10. Follow the connection steps
Running the software repair on Bridge for Mac:
1. Launch Bridge for MAC without the handset connected.
2. On the Main Window select "Xperia > Repair Xperia Device".
3. Ensure the phone is charged and select "Ok" in the following window.
4. Select Continue on the following page.
5. Wait until the initialising step is finished the continue as below.
6 . Select your model of phone from the list that appears
7. Follow the connection steps that appear, ensuring that you are holding the relevant button down before during and after the connection phase until the update/repair begins.
