How to reset my phone?

[hylomantis]

i have gotten an used Sony Xperia SP c5303. it is still protected by the lockscreen combination. how can i hard reset the phone? the companion program does not work, because when i connect it to my PC it tells me to unlock the phone first. i have tried to hard reset by using certain button combinations. like holding volume up and volume down and power button at the same time. but it just turns on the phone. what can i do to hard reset it? it does not contain a simcard.

[Uliwooly]

@hylomantis

Simple, you will have to contact the seler to get the pattern/pin/password. 

[hylomantis]

i have gotten it to work by not connecting the phone yet. first when i opened the program and i connected the phone to my pc, it told me to unlock the phone. but i found out that if you don't connect the phone and go to the repair section of the program first and follow the steps. then later it tells you to connect the phone to the computer while holding volume down button. and then everthing worked.