I've read similar articles here in Stackoverflow, but i can't seem to make it work in my case.

I have column named (Date), with data type varchar, and the data throughout the whole column looks like this (1999-12-31-23-00-01) without parenthesis.

So, instead of Varchar, I want the same value, but in datetime format.

This is my table structure:

CREATE TABLE App
(

[ID] [int] IDENTITY(1,1) NOT NULL,

[Date] Varchar(50) NULL,

[Inst.nr] [smallint] NULL,

[Creator Initials] varchar NULL,

[AppOwner] varchar NULL,

[Status] varchar NULL,

[Serial.Nr] varchar NULL,

[MAC.Addr] varchar NULL,

[Dell.nr] varchar NULL,

[Model] varchar NULL,

[Description] varchar NULL,

[Service Warranty] [date] NULL,

[Purchased] [date] NULL,
)

Actually, the problem is not with the structure, its some old data from an Excel file, which was imported into SQL database. 
In my [Date] column, which is in Varchar right now, The data inside this column looks like this 1999-12-31-23-00-01

As you can see, it looks like a datetime format, but it won't accept the conversion from varchar to datetime