Samsung Galaxy S2 Plus I9105P data:
GSM frequencies :850 900 1800 1900
Standard UMTS :850 900 1900 2100
Type :Touch
Dimensions (W x H x D) :125,30 x 66,10 x 8,98 mm
Weight :121,00 g
Main display :Color / Super AMOLED Plus
16M colors
480 x 800 px (4.30") 217 ppi
Talk time (max.) :2G: 1091 min. (18,2 h)
3G: 540 min. (9,0 h)
Stand-by (max.) :2G: 714 h. (29,8 days)
3G: 320 h. (13,3 days)
Standard battery :Li-Ion 1650 mAh
Internal memory :8 GB
RAM memory :1 GB
Memory cards : microSD, microSDHC, microSDXC (up to 64 GB)
Operating system :Android 4.1.2 Jelly Bean
Processor :Broadcom BCM28155
Processor clock :1,20 GHz
Touchscreen : yes
SAR (10g) :0,327 W/kg
How to hard reset:
If you forgot the combination to unlock the screen follow these steps:
Warning! All data will be lost!
1.Power off your phone
2.Press together volume up + home key + power button
3.Choose with volume buttons "wipe data/factory reset" and select it with power button
4.Choose "yes" with volume buttons and select it with power button
5.Wait untill format ends
6.Choose "reboot"
7.Wait until the phone restarts
That's all
Here is video how to do: