He has been a peripheral figure in the Blades squad this season, and according to newspaper reporters the manager is willing to use him as leverage to sign Jermaine Beckford from Leeds.
But Blackwell says Sharp, 23, has every chance of re-establishing himself at the club next season.
"Everybody's got the same opportunity, they return pre-season with the same level playing field," he told BBC Radio Sheffield.
"You've got to fight for the right to be a Blade and players have got to work hard to be a Blade."
The Swansea City manager Roberto Martinez appears destined to leave the Liberty Stadium this summer after admitting his interest in becoming the next Celtic boss.
The Scottish side have made an official approach for the Spaniard, who is also wanted by Real Sociedad.
"Managing Celtic is one of the top jobs in European football, any young aspiring manager with ambition would be interested in a job like that." Martinez told the Glasgow Evening Times.
"Everything has to be sorted with Swansea first. I have an agreement in place with the Swansea chairman as to what would happen and I'd want that to be honoured."
Swansea have signed the winger Nathan Dyer from Southampton for £400,000. Dyer, 21, spent five months on loan at the Liberty Stadium this season.
The move helps secure the short-term future of Southampton, who have been unable to pay wages of staff due to a financial crisis. They have been relegated to League One.
Richard Hinds has agreed a two-year contract to remain at Sheffield Wednesday.
Hinds, 28, moved to Hillsborough on a Bosman transfer from the Iron in the summer of 2007. He spent much of last season out with a broken leg.
"Richard showed tremendous character and determination to come back from serious injury last season ahead of schedule to play a key role in our defence towards the end of the season," said the Owls manager Brian Laws.
"He has now fully recovered from his broken leg and will be striving to make up for lost time next season."
Crystal Palace have signed the midfielder Darren Ambrose on a two-year contract from relegated Charlton Athletic.