Hello, i have removed securitytool with malwarebytes,but after removal i cant see my desktop icon & taskbar.
More aboutdesktop icons showing
CTRL+ALT+DEL in the Task Manager under the Application tab click the "New Task" button in the box type: explorer.exe
In addition to Emerald's advice, what you're seeing (or rather not seeing) is a clear indication part of the threat remains. You might want to take a trip to http://www.bleepingcomputer.com and seek out the tutorial for running ComboFix before downloading it from their mirror and carefully following the on-screen instructions.
Before doing any of that, I suggest you download CCleaner from http://www.piriform.com and ATF Cleaner from http://www.atribune.org and use both to clear out the clutter which includes the hiding places for the stuff the so-called SecurityTool brought in.