My Mediatek usb flash drive is not get detected.

The o/p of lsusb

falguni@falguni-M61PME-S2P:~$ lsusb
Bus 002 Device 002: ID 0e8d:0003 MediaTek Inc.
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub

and the o/p of usb-devices

falguni@falguni-M61PME-S2P:~$ usb-devices

T:  Bus=01 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#=  1 Spd=480 MxCh=10
D:  Ver= 2.00 Cls=09(hub  ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
P:  Vendor=1d6b ProdID=0002 Rev=03.05
S:  Manufacturer=Linux 3.5.0-18-generic ehci_hcd
S:  Product=EHCI Host Controller
S:  SerialNumber=0000:00:02.1
C:  #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=0mA
I:  If#= 0 Alt= 0 #EPs= 1 Cls=09(hub  ) Sub=00 Prot=00 Driver=hub

T:  Bus=02 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#=  1 Spd=12  MxCh=10
D:  Ver= 1.10 Cls=09(hub  ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
P:  Vendor=1d6b ProdID=0001 Rev=03.05
S:  Manufacturer=Linux 3.5.0-18-generic ohci_hcd
S:  Product=OHCI Host Controller
S:  SerialNumber=0000:00:02.0
C:  #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=0mA
I:  If#= 0 Alt= 0 #EPs= 1 Cls=09(hub  ) Sub=00 Prot=00 Driver=hub

But in 12.04, the o/p of usb-devices was:

falguni@falguni-M61PME-S2P:~$ usb-devices

T:  Bus=01 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#=  1 Spd=480 MxCh=10
D:  Ver= 2.00 Cls=09(hub  ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
P:  Vendor=1d6b ProdID=0002 Rev=03.05
S:  Manufacturer=Linux 3.5.0-18-generic ehci_hcd
S:  Product=EHCI Host Controller
S:  SerialNumber=0000:00:02.1
C:  #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=0mA
I:  If#= 0 Alt= 0 #EPs= 1 Cls=09(hub  ) Sub=00 Prot=00 Driver=hub

T:  Bus=02 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#=  1 Spd=12  MxCh=10
D:  Ver= 1.10 Cls=09(hub  ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
P:  Vendor=1d6b ProdID=0001 Rev=03.05
S:  Manufacturer=Linux 3.5.0-18-generic ohci_hcd
S:  Product=OHCI Host Controller
S:  SerialNumber=0000:00:02.0
C:  #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=0mA
I:  If#= 0 Alt= 0 #EPs= 1 Cls=09(hub  ) Sub=00 Prot=00 Driver=hub

T:  Bus=02 Lev=01 Prnt=01 Port=04 Cnt=01 Dev#=  2 Spd=12  MxCh= 0
D:  Ver= 2.00 Cls=02(commc) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
P:  Vendor=0e8d ProdID=0003 Rev=02.00
S:  Manufacturer=MediaTek Inc
S:  Product=MT6235 
C:  #Ifs= 2 Cfg#= 1 Atr=80 MxPwr=500mA
I:  If#= 0 Alt= 0 #EPs= 2 Cls=0a(data ) Sub=00 Prot=00 Driver=cdc_acm
I:  If#= 1 Alt= 0 #EPs= 1 Cls=02(commc) Sub=02 Prot=01 Driver=cdc_acm

It was working fine in 12.04. Now after upgrading to 12.10 the problem started.

Where is the problem and how to solve it?