Hi @Sesth, welcome to our forum!
What do you need assistance with? Is the device for example, slow and not as fast as it used to be?
A good place to start is making sure that you have some free storage on the device. We recommend that you have at least 5% of the internal storage free so apps can save the data that they need and for all functions to work properly.
Please do elaborate a bit! 
my device not power on sony xepria screen on and off that is coming on screen and on off
Hi @aditaapate, sorry to hear that. 
Have you tried removing the SIM and/or SD card(s) from the device and powered it on again? If you haven't done that, please do.
If there is no change after removing the card(s), perform a software repair using Xperia Companion.
This will delete all data stored on the internal storage and a backup is not possible.
Let me know if that helps!
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